The following outline is provided as an overview of and topical guide to astronomy:
Astronomy
Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall evolution. Objects of interest includ ...
– studies the
universe
The universe is all of space and time and their contents. It comprises all of existence, any fundamental interaction, physical process and physical constant, and therefore all forms of matter and energy, and the structures they form, from s ...
physics
Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge whi ...
,
chemistry
Chemistry is the scientific study of the properties and behavior of matter. It is a physical science within the natural sciences that studies the chemical elements that make up matter and chemical compound, compounds made of atoms, molecules a ...
,
meteorology
Meteorology is the scientific study of the Earth's atmosphere and short-term atmospheric phenomena (i.e. weather), with a focus on weather forecasting. It has applications in the military, aviation, energy production, transport, agricultur ...
, and
motion
In physics, motion is when an object changes its position with respect to a reference point in a given time. Motion is mathematically described in terms of displacement, distance, velocity, acceleration, speed, and frame of reference to an o ...
galaxies
A galaxy is a system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar Sys ...
,
planet
A planet is a large, Hydrostatic equilibrium, rounded Astronomical object, astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets b ...
s, etc.) and
phenomena
A phenomenon ( phenomena), sometimes spelled phaenomenon, is an observable Event (philosophy), event. The term came into its modern Philosophy, philosophical usage through Immanuel Kant, who contrasted it with the noumenon, which ''cannot'' be ...
that originate outside the
atmosphere of Earth
The atmosphere of Earth is composed of a layer of gas mixture that surrounds the Earth's planetary surface (both lands and oceans), known collectively as air, with variable quantities of suspended aerosols and particulates (which create weather ...
astrobiology
Astrobiology (also xenology or exobiology) is a scientific field within the List of life sciences, life and environmental sciences that studies the abiogenesis, origins, Protocell, early evolution, distribution, and future of life in the univ ...
, studying potential life throughout the universe.
Nature of astronomy
Astronomy can be described as all the following:
* An
academic discipline
An academic discipline or academic field is a subdivision of knowledge that is taught and researched at the college or university level. Disciplines are defined (in part) and recognized by the academic journals in which research is published, a ...
: one with academic departments, curricula and degrees; national and international societies; and specialized journals.
* A scientific field (a branch of
science
Science is a systematic discipline that builds and organises knowledge in the form of testable hypotheses and predictions about the universe. Modern science is typically divided into twoor threemajor branches: the natural sciences, which stu ...
) – widely recognized category of specialized expertise within science, and typically embodies it
** A
natural science
Natural science or empirical science is one of the branches of science concerned with the description, understanding and prediction of natural phenomena, based on empirical evidence from observation and experimentation. Mechanisms such as peer ...
– one that seeks to elucidate the rules that govern the
natural
Nature is an inherent character or constitution, particularly of the ecosphere or the universe as a whole. In this general sense nature refers to the laws, elements and phenomena of the physical world, including life. Although humans are part ...
world using
empirical
Empirical evidence is evidence obtained through sense experience or experimental procedure. It is of central importance to the sciences and plays a role in various other fields, like epistemology and law.
There is no general agreement on how t ...
and
scientific method
The scientific method is an Empirical evidence, empirical method for acquiring knowledge that has been referred to while doing science since at least the 17th century. Historically, it was developed through the centuries from the ancient and ...
s.
*** A branch or field of
space science
Space is a three-dimensional continuum containing positions and directions. In classical physics, physical space is often conceived in three linear dimensions. Modern physicists usually consider it, with time, to be part of a boundless ...
curiosity
Curiosity (from Latin , from "careful, diligent, curious", akin to "care") is a quality related to inquisitive thinking, such as exploration, investigation, and learning, evident in humans and other animals. Curiosity helps Developmental psyc ...
or appreciation of
beauty
Beauty is commonly described as a feature of objects that makes them pleasure, pleasurable to perceive. Such objects include landscapes, sunsets, humans and works of art. Beauty, art and taste are the main subjects of aesthetics, one of the fie ...
, the latter especially including
astrophotography
Astrophotography, also known as astronomical imaging, is the photography or imaging of astronomical objects, celestial events, or areas of the night sky. The first photograph of an astronomical object (the Moon) was taken in 1839, but it was no ...
.
Branches
*
Astrobiology
Astrobiology (also xenology or exobiology) is a scientific field within the List of life sciences, life and environmental sciences that studies the abiogenesis, origins, Protocell, early evolution, distribution, and future of life in the univ ...
– studies the advent and
evolution
Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...
of
biological system
A biological system is a complex Biological network inference, network which connects several biologically relevant entities. Biological organization spans several scales and are determined based different structures depending on what the system is ...
s in the universe.
*
Astrophysics
Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline, James Keeler, said, astrophysics "seeks to ascertain the ...
– branch of
astronomy
Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall evolution. Objects of interest includ ...
that deals with the
physics
Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge whi ...
of the universe, including the physical properties of celestial objects, as well as their interactions and behavior. Among the objects studied are galaxies,
star
A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...
s, planets,
exoplanet
An exoplanet or extrasolar planet is a planet outside the Solar System. The first confirmed detection of an exoplanet was in 1992 around a pulsar, and the first detection around a main-sequence star was in 1995. A different planet, first det ...
s, the
interstellar medium
The interstellar medium (ISM) is the matter and radiation that exists in the outer space, space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as cosmic dust, dust and cosmic rays. It f ...
and the
cosmic microwave background
The cosmic microwave background (CMB, CMBR), or relic radiation, is microwave radiation that fills all space in the observable universe. With a standard optical telescope, the background space between stars and galaxies is almost completely dar ...
; and the properties examined include
luminosity
Luminosity is an absolute measure of radiated electromagnetic radiation, electromagnetic energy per unit time, and is synonymous with the radiant power emitted by a light-emitting object. In astronomy, luminosity is the total amount of electroma ...
,
density
Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be u ...
,
temperature
Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness. Temperature is measurement, measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making ...
, and
chemical
A chemical substance is a unique form of matter with constant chemical composition and characteristic properties. Chemical substances may take the form of a single element or chemical compounds. If two or more chemical substances can be combin ...
composition. The subdisciplines of theoretical astrophysics are:
** Compact objects – this subdiscipline studies very dense matter in
white dwarf
A white dwarf is a Compact star, stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very density, dense: in an Earth sized volume, it packs a mass that is comparable to the Sun. No nuclear fusion takes place i ...
s and
neutron star
A neutron star is the gravitationally collapsed Stellar core, core of a massive supergiant star. It results from the supernova explosion of a stellar evolution#Massive star, massive star—combined with gravitational collapse—that compresses ...
s and their effects on environments including accretion.
**
Physical cosmology
Physical cosmology is a branch of cosmology concerned with the study of cosmological models. A cosmological model, or simply cosmology, provides a description of the largest-scale structures and dynamics of the universe and allows study of fu ...
– origin and evolution of the universe as a whole. The study of cosmology is theoretical astrophysics at its largest scale.
** Quantum cosmology - the study of cosmology through the use of
quantum field theory
In theoretical physics, quantum field theory (QFT) is a theoretical framework that combines Field theory (physics), field theory and the principle of relativity with ideas behind quantum mechanics. QFT is used in particle physics to construct phy ...
to explain phenomena
general relativity
General relativity, also known as the general theory of relativity, and as Einstein's theory of gravity, is the differential geometry, geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of grav ...
cannot due to limitations in its framework.
**
Computational astrophysics
Computational astrophysics refers to the methods and computing tools developed and used in astrophysics research. Like computational chemistry or computational physics, it is both a specific branch of theoretical astrophysics and an interdiscip ...
– The study of astrophysics using computational methods and tools to develop computational models.
**
Galactic astronomy
Galactic astronomy is the study of the Milky Way galaxy and all its contents. This is in contrast to extragalactic astronomy, which is the study of everything outside our galaxy, including all other galaxies.
Galactic astronomy should not be con ...
– deals with the structure and components of our Galaxy and of other galaxies.
** High energy astrophysics – studies phenomena occurring at high energies including
active galactic nuclei
An active galactic nucleus (AGN) is a compact region at the center of a galaxy that emits a significant amount of energy across the electromagnetic spectrum, with characteristics indicating that this luminosity is not produced by the stars. Such e ...
,
supernova
A supernova (: supernovae or supernovas) is a powerful and luminous explosion of a star. A supernova occurs during the last stellar evolution, evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion ...
e,
gamma-ray burst
In gamma-ray astronomy, gamma-ray bursts (GRBs) are extremely energetic events occurring in distant Galaxy, galaxies which represent the brightest and most powerful class of explosion in the universe. These extreme Electromagnetic radiation, ele ...
s,
quasar
A quasar ( ) is an extremely Luminosity, luminous active galactic nucleus (AGN). It is sometimes known as a quasi-stellar object, abbreviated QSO. The emission from an AGN is powered by accretion onto a supermassive black hole with a mass rangi ...
s, and
shock
Shock may refer to:
Common uses
Healthcare
* Acute stress reaction, also known as psychological or mental shock
** Shell shock, soldiers' reaction to battle trauma
* Circulatory shock, a medical emergency
** Cardiogenic shock, resulting from ...
interstellar medium
The interstellar medium (ISM) is the matter and radiation that exists in the outer space, space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as cosmic dust, dust and cosmic rays. It f ...
,
intergalactic medium
Intergalactic may refer to:
* "Intergalactic" (song), a song by the Beastie Boys
* ''Intergalactic'' (TV series), a 2021 UK science fiction TV series
* Intergalactic space
* Intergalactic travel, travel between galaxies in science fiction and ...
and
dust
Dust is made of particle size, fine particles of solid matter. On Earth, it generally consists of particles in the atmosphere that come from various sources such as soil lifted by wind (an aeolian processes, aeolian process), Types of volcan ...
.
**
Extragalactic astronomy
Extragalactic astronomy is the branch of astronomy concerned with objects outside the Milky Way galaxy. In other words, it is the study of all astronomical objects which are not covered by galactic astronomy.
The closest objects in extragalactic ...
– study of objects (mainly galaxies) outside our Galaxy, including
galaxy formation and evolution
In cosmology, the study of galaxy formation and evolution is concerned with the processes that formed a heterogeneous universe from a homogeneous beginning, the formation of the first galaxies, the way galaxies change over time, and the process ...
.
**
Stellar astronomy
Astronomy is a natural science that studies astronomical object, celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall chronology of the U ...
– concerned with
Star formation
Star formation is the process by which dense regions within molecular clouds in interstellar space—sometimes referred to as "stellar nurseries" or "star-forming regions"—Jeans instability, collapse and form stars. As a branch of astronomy, sta ...
, physical properties,
main sequence
In astronomy, the main sequence is a classification of stars which appear on plots of stellar color index, color versus absolute magnitude, brightness as a continuous and distinctive band. Stars on this band are known as main-sequence stars or d ...
stellar evolution
Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is consi ...
and extinction.
**
Plasma astrophysics
Astrophysical plasma is plasma (physics), plasma outside of the Solar System. It is studied as part of astrophysics and is commonly observed in space. The accepted view of scientists is that much of the baryonic matter in the universe exists in th ...
Relativistic astrophysics
Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline, James Keeler, said, astrophysics "seeks to ascertain the ...
– studies effects of
special relativity
In physics, the special theory of relativity, or special relativity for short, is a scientific theory of the relationship between Spacetime, space and time. In Albert Einstein's 1905 paper, Annus Mirabilis papers#Special relativity,
"On the Ele ...
and
general relativity
General relativity, also known as the general theory of relativity, and as Einstein's theory of gravity, is the differential geometry, geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of grav ...
in astrophysical contexts including
gravitational waves
Gravitational waves are oscillations of the gravitational field that travel through space at the speed of light; they are generated by the relative motion of gravitating masses. They were proposed by Oliver Heaviside in 1893 and then later by H ...
,
gravitational lens
A gravitational lens is matter, such as a galaxy cluster, cluster of galaxies or a point particle, that bends light from a distant source as it travels toward an observer. The amount of gravitational lensing is described by Albert Einstein's Ge ...
ing and
black hole
A black hole is a massive, compact astronomical object so dense that its gravity prevents anything from escaping, even light. Albert Einstein's theory of general relativity predicts that a sufficiently compact mass will form a black hole. Th ...
s.
**
Solar physics
Solar physics is the branch of astrophysics that specializes in the study of the Sun. It intersects with many disciplines of pure physics and astrophysics.
Because the Sun is uniquely situated for close-range observing (other stars cannot be re ...
– Sun and its interaction with the remainder of the Solar System and interstellar space.
*
Planetary Science
Planetary science (or more rarely, planetology) is the scientific study of planets (including Earth), celestial bodies (such as moons, asteroids, comets) and planetary systems (in particular those of the Solar System) and the processes of ...
– study of planets, moons, and planetary systems.
**
Atmospheric science
Atmospheric science is the study of the Atmosphere of Earth, Earth's atmosphere and its various inner-working physical processes. Meteorology includes atmospheric chemistry and atmospheric physics with a major focus on weather forecasting. Clima ...
– study of atmospheres and weather.
**
Exoplanetology
This page describes exoplanet orbital and physical parameters.
Orbital parameters
Most known extrasolar planet candidates have been discovered using indirect methods and therefore only some of their physical and orbital parameters can be determi ...
– various planets outside of the Solar System
** Planetary formation – formation of planets and moons in the context of the
formation and evolution of the Solar System
There is evidence that the formation of the Solar System began about 4.6 billion years ago with the gravitational collapse of a small part of a giant molecular cloud. Most of the collapsing mass collected in the center, forming the Sun, while ...
.
**
Planetary rings
A ring system is a disc or torus orbiting an astronomical object that is composed of solid material such as dust, meteoroids, planetoids, moonlets, or stellar objects.
Ring systems are best known as planetary rings, common components of sate ...
– dynamics, stability, and composition of planetary rings
**
Magnetosphere
In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior Dynamo ...
s – magnetic fields of planets and moons
**
Planetary surface
A planetary surface is where the solid or liquid material of certain types of astronomical objects contacts the atmosphere or outer space. Planetary surfaces are found on solid objects of planetary mass, including terrestrial planets (including ...
s – surface geology of planets and moons
** Planetary interiors – interior composition of planets and moons
**
Small Solar System bodies
A small Solar System body (SSSB) is an object in the Solar System that is neither a planet, a dwarf planet, nor a natural satellite. The term was first IAU definition of planet, defined in 2006 by the International Astronomical Union (IAU) as fo ...
– smallest bodies, including
asteroid
An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...
s,
comet
A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...
s, Kuiper belt objects, and dust.
* Astronomy divided by general technique used for astronomical research:
**
Astrometry
Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other Astronomical object, celestial bodies. It provides the kinematics and physical origin of the Solar System and this galaxy, th ...
– study of the position of objects in the sky and their changes of position. Defines the system of coordinates used and the
kinematics
In physics, kinematics studies the geometrical aspects of motion of physical objects independent of forces that set them in motion. Constrained motion such as linked machine parts are also described as kinematics.
Kinematics is concerned with s ...
of objects in our Galaxy.
**
Observational astronomy
Observational astronomy is a division of astronomy that is concerned with recording data about the observable universe, in contrast with theoretical astronomy, which is mainly concerned with calculating the measurable implications of physical ...
– practice of observing celestial objects by using telescopes and other astronomical apparatus. It is concerned with recording data. The subdisciplines of
observational astronomy
Observational astronomy is a division of astronomy that is concerned with recording data about the observable universe, in contrast with theoretical astronomy, which is mainly concerned with calculating the measurable implications of physical ...
are generally made by the specifications of the detectors, specifically the ranges of wavelengths observed:
***
Radio astronomy
Radio astronomy is a subfield of astronomy that studies Astronomical object, celestial objects using radio waves. It started in 1933, when Karl Jansky at Bell Telephone Laboratories reported radiation coming from the Milky Way. Subsequent observat ...
– Above 300 μm
***
Submillimetre astronomy
Submillimetre astronomy or submillimeter astronomy (see spelling differences) is the branch of observational astronomy that is conducted at submillimetre wavelengths (i.e., terahertz radiation) of the electromagnetic spectrum. Astronomers plac ...
– 200 μm to 1 mm
***
Infrared astronomy
Infrared astronomy is a sub-discipline of astronomy which specializes in the astronomical observation, observation and analysis of astronomical objects using infrared (IR) radiation. The wavelength of infrared light ranges from 0.75 to 300 microm ...
– 0.7–350 μm
***
Optical astronomy
Visible-light astronomy encompasses a wide variety of astronomical observation via telescopes that are sensitive in the range of visible light (optical telescopes). Visible-light astronomy is part of optical astronomy, and differs from astronomi ...
X-ray astronomy
X-ray astronomy is an observational branch of astronomy which deals with the study of X-ray observation and detection from astronomical objects. X-radiation is absorbed by the Earth's atmosphere, so instruments to detect X-rays must be taken to ...
– 0.01–10 nm
***
Gamma-ray astronomy
Gamma-ray astronomy is a subfield of astronomy where scientists observe and study celestial objects and phenomena in outer space which emit cosmic electromagnetic radiation in the form of gamma rays,Astronomical literature generally hyphena ...
Cosmic ray
Cosmic rays or astroparticles are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the ...
s, including plasma
***
Neutrino astronomy
Neutrino astronomy is a branch of astronomy that gathers information about astronomical objects by observing and studying neutrinos emitted by them with the help of neutrino detectors in special Earth observatories. It is an emerging field in as ...
–
Neutrino
A neutrino ( ; denoted by the Greek letter ) is an elementary particle that interacts via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass is so small ('' -ino'') that i ...
Cosmic dust
Cosmic dustalso called extraterrestrial dust, space dust, or star dustis dust that occurs in outer space or has fallen onto Earth. Most cosmic dust particles measure between a few molecules and , such as micrometeoroids (30 μm). Cosmic dust can ...
Graviton
In theories of quantum gravity, the graviton is the hypothetical elementary particle that mediates the force of gravitational interaction. There is no complete quantum field theory of gravitons due to an outstanding mathematical problem with re ...
s
**
Photometry
Photometry can refer to:
* Photometry (optics), the science of measurement of visible light in terms of its perceived brightness to human vision
* Photometry (astronomy), the measurement of the flux or intensity of an astronomical object's electr ...
– study of how bright celestial objects are when passed through different filters
**
Spectroscopy
Spectroscopy is the field of study that measures and interprets electromagnetic spectra. In narrower contexts, spectroscopy is the precise study of color as generalized from visible light to all bands of the electromagnetic spectrum.
Spectro ...
– study of the spectra of astronomical objects
* Other disciplines that may be considered part of astronomy:
**
Archaeoastronomy
Archaeoastronomy (also spelled archeoastronomy) is the interdisciplinary or multidisciplinary study of how people in the past "have understood the phenomena in the sky, how they used these phenomena and what role the sky played in their cultur ...
**
Astrochemistry
Astrochemistry is the study of the abundance and reactions of molecules in the universe, and their interaction with radiation. The discipline is an overlap of astronomy and chemistry. The word "astrochemistry" may be applied to both the Solar Syst ...
History
History of astronomy
The history of astronomy focuses on the contributions civilizations have made to further their understanding of the universe beyond earth's atmosphere.
Astronomy is one of the oldest natural sciences, achieving a high level of success in the sec ...
Geocentric model
In astronomy, the geocentric model (also known as geocentrism, often exemplified specifically by the Ptolemaic system) is a superseded scientific theories, superseded description of the Universe with Earth at the center. Under most geocentric m ...
**
Heliocentrism
Heliocentrism (also known as the heliocentric model) is a superseded astronomical model in which the Earth and planets orbit around the Sun at the center of the universe. Historically, heliocentrism was opposed to geocentrism, which placed t ...
***
Copernican heliocentrism
Copernican heliocentrism is the astronomical scientific modeling, model developed by Nicolaus Copernicus and published in 1543. This model positioned the Sun at the center of the Universe, motionless, with Earth and the other planets orbiting arou ...
***
Tychonic system
The Tychonic system (or Tychonian system) is a model of the universe published by Tycho Brahe in 1588, which combines what he saw as the mathematical benefits of the Copernican heliocentrism, Copernican system with the philosophical and "physic ...
*
Archaeoastronomy
Archaeoastronomy (also spelled archeoastronomy) is the interdisciplinary or multidisciplinary study of how people in the past "have understood the phenomena in the sky, how they used these phenomena and what role the sky played in their cultur ...
Babylonian astronomy
Babylonian astronomy was the study or recording of celestial objects during the early history of Mesopotamia. The numeral system used, sexagesimal, was based on 60, as opposed to ten in the modern decimal system. This system simplified the ca ...
**
Chinese astronomy
Astronomy in China has a long history stretching from the Shang dynasty, being refined over a period of more than 3,000 years. The Ancient China, ancient Chinese people have identified stars from 1300 BCE, as Chinese star names later categori ...
**
Egyptian astronomy
Egyptian astronomy started in prehistory, prehistoric times, in the Prehistoric Egypt, Predynastic Period. In the 5th millennium BCE, the stone circles at Nabta Playa may have made use of astronomical alignments. By the time the historical Ancie ...
**
Greek astronomy
Ancient Greek astronomy is the astronomy written in the Greek language during classical antiquity. Greek astronomy is understood to include the Ancient Greece, Ancient Greek, Hellenistic period, Hellenistic, Roman Empire, Greco-Roman, and Late an ...
Indian astronomy
Astronomy has a long history in the Indian subcontinent, stretching from History of India, pre-historic to History of India (1947–present), modern times. Some of the earliest roots of Indian astronomy can be dated to the period of Indus Valle ...
**
Islamic astronomy
Medieval Islamic astronomy comprises the astronomical developments made in the Islamic world, particularly during the Islamic Golden Age (9th–13th centuries), and mostly written in the Arabic language. These developments mostly took place in th ...
Astronomy in medieval Islam
Medieval Islamic astronomy comprises the Astronomy, astronomical developments made in the Islamic world, particularly during the Islamic Golden Age (9th–13th centuries), and mostly written in the Arabic language. These developments mostly took ...
Copernican Revolution
The term "Copernican Revolution" was coined by the German philosopher Immanuel Kant in his 1781 work ''Critique of Pure Reason''. It was the paradigm shift from the Ptolemaic model of the heavens, which described the cosmos as having Earth sta ...
****
Copernican heliocentrism
Copernican heliocentrism is the astronomical scientific modeling, model developed by Nicolaus Copernicus and published in 1543. This model positioned the Sun at the center of the Universe, motionless, with Earth and the other planets orbiting arou ...
****
Nicolaus Copernicus
Nicolaus Copernicus (19 February 1473 – 24 May 1543) was a Renaissance polymath who formulated a mathematical model, model of Celestial spheres#Renaissance, the universe that placed heliocentrism, the Sun rather than Earth at its cen ...
***** ''
On the Revolutions of the Heavenly Spheres
''De revolutionibus orbium coelestium'' (English translation: ''On the Revolutions of the Heavenly Spheres'') is the seminal work on the Copernican heliocentrism, heliocentric theory of the astronomer Nicolaus Copernicus (1473–1543) of the Rena ...
''
****
Tycho Brahe
Tycho Brahe ( ; ; born Tyge Ottesen Brahe, ; 14 December 154624 October 1601), generally called Tycho for short, was a Danish astronomer of the Renaissance, known for his comprehensive and unprecedentedly accurate astronomical observations. He ...
*****
Tychonic system
The Tychonic system (or Tychonian system) is a model of the universe published by Tycho Brahe in 1588, which combines what he saw as the mathematical benefits of the Copernican heliocentrism, Copernican system with the philosophical and "physic ...
****
Galileo Galilei
Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 – 8 January 1642), commonly referred to as Galileo Galilei ( , , ) or mononymously as Galileo, was an Italian astronomer, physicist and engineer, sometimes described as a poly ...
***** ''
Dialogue Concerning the Two Chief World Systems
''Dialogue Concerning the Two Chief World Systems'' (''Dialogo sopra i due massimi sistemi del mondo'') is a 1632 book by Galileo Galilei comparing Nicolaus Copernicus's Copernican heliocentrism, heliocentric system model with Ptolemy's geocen ...
'' defense of the heliocentric system written by Galileo, which led to his trial and house arrest by the Inquisition.
***
Invention of the telescope
The history of the telescope can be traced to before the invention of the earliest known telescope, which appeared in 1608 in the Netherlands, when a patent was submitted by Hans Lippershey, an eyeglass maker. Although Lippershey did not recei ...
Atmosphere
An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...
*
Celestial pole
The north and south celestial poles are the two points in the sky where Earth's axis of rotation, indefinitely extended, intersects the celestial sphere. The north and south celestial poles appear permanently directly overhead to observers at ...
*
Eclipse
An eclipse is an astronomical event which occurs when an astronomical object or spacecraft is temporarily obscured, by passing into the shadow of another body or by having another body pass between it and the viewer. This alignment of three ...
*
Ecliptic
The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making.
Fr ...
*
Cosmic rays
Cosmic rays or astroparticles are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar ...
*
Kepler's laws
In astronomy, Kepler's laws of planetary motion, published by Johannes Kepler in 1609 (except the third law, which was fully published in 1619), describe the orbits of planets around the Sun. These laws replaced circular orbits and epicycles in ...
*
Doppler effect
The Doppler effect (also Doppler shift) is the change in the frequency of a wave in relation to an observer who is moving relative to the source of the wave. The ''Doppler effect'' is named after the physicist Christian Doppler, who described ...
*
Nutation
Nutation () is a rocking, swaying, or nodding motion in the axis of rotation of a largely axially symmetric object, such as a gyroscope, planet, or bullet in flight, or as an intended behaviour of a mechanism. In an appropriate reference fra ...
*
Orbit
In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an ...
Precession
Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In o ...
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Proper motion
Proper motion is the astrometric measure of changes in the apparent places of stars or other celestial objects as they move relative to the center of mass of the Solar System. It is measured relative to the distant stars or a stable referenc ...
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Redshift
In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and increase in frequency and e ...
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Solar eclipse
A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring the view of the Sun from a small part of Earth, totally or partially. Such an alignment occurs approximately every six months, during the eclipse season i ...
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Tides
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another.
Tide tables ...
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Zodiac
The zodiac is a belt-shaped region of the sky that extends approximately 8° north and south celestial latitude of the ecliptic – the apparent path of the Sun across the celestial sphere over the course of the year. Within this zodiac ...
Astronomical objects
Astronomical object
An astronomical object, celestial object, stellar object or heavenly body is a naturally occurring physical entity, association, or structure that exists within the observable universe. In astronomy, the terms ''object'' and ''body'' are of ...
Solar System
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Solar System
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...
List of Solar System objects
The following is a list of Solar System objects by orbit, ordered by increasing distance from the Sun. Most named objects in this list have a diameter of 500 km or more.
*The Sun, a spectral class G2V main-sequence star
*The inner Solar Sy ...
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List of Solar System objects by size
This article includes a list of the most massive known objects of the Solar System and partial lists of smaller objects by observed mean radius. These lists can be sorted according to an object's radius and mass and, for the most massive objects, ...
Halley's comet
Halley's Comet is the only known List of periodic comets, short-period comet that is consistently visible to the naked eye from Earth, appearing every 72–80 years, though with the majority of recorded apparitions (25 of 30) occurring after ...
Sun
Sun
The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...
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Milky Way
The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the #Appearance, galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galax ...
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Solar System
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...
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Stellar classification
In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction gratin ...
Solar core
The core of the Sun is considered to extend from the center to about 0.2 of the solar radius (). It is the hottest part of the Sun and of the Solar System. It has a density of at the center, and a temperature of 15 million kelvins (15 million de ...
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Radiation zone
A radiative zone is a layer of a star's interior where energy is primarily transported toward the exterior by means of radiative diffusion and thermal conduction, rather than by convection. Energy travels through the radiative zone in the form of ...
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Convection zone
A convection zone, convective zone or convective region of a star is a layer which is unstable due to convection. Energy is primarily or partially transported by convection in such a region. In a radiation zone, energy is transported by radiation ...
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Stellar atmosphere
The stellar atmosphere is the outer region of the volume of a star, lying above the stellar core, radiation zone and convection zone.
Overview
The stellar atmosphere is divided into several regions of distinct character:
* The photosphere, whi ...
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Photosphere
The photosphere is a star's outer shell from which light is radiated. It extends into a star's surface until the plasma becomes opaque, equivalent to an optical depth of approximately , or equivalently, a depth from which 50% of light will esc ...
Sunspot
Sunspots are temporary spots on the Sun's surface that are darker than the surrounding area. They are one of the most recognizable Solar phenomena and despite the fact that they are mostly visible in the solar photosphere they usually aff ...
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Chromosphere
A chromosphere ("sphere of color", from the Ancient Greek words χρῶμα (''khrôma'') 'color' and σφαῖρα (''sphaîra'') 'sphere') is the second layer of a Stellar atmosphere, star's atmosphere, located above the photosphere and below t ...
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Plage
Plage may refer to:
*Solar plage, a bright region in the chromosphere of the Sun
*Plage (mycology), a clear, unornamented area on the basal area of an ornamented fungal spore
* "Plage" (song), a 2011 song by English electronic band Crystal Fighter ...
Solar corona
In astronomy, a corona (: coronas or coronae) is the outermost layer of a star's Stellar atmosphere, atmosphere. It is a hot but relatively luminosity, dim region of Plasma (physics), plasma populated by intermittent coronal structures such as so ...
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Solar transition region
The solar transition region is a region of the Sun's atmosphere between the upper chromosphere and corona. It is important because it is the site of several unrelated but important transitions in the physics of the solar atmosphere:
* Below, gr ...
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Coronal hole
Coronal holes are regions of the Sun's corona that emit low levels of ultraviolet and X-ray radiation compared to their surroundings. They are composed of relatively cool and tenuous plasma (physics), plasma permeated by magnetic fields that are o ...
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Coronal loop
In solar physics, a coronal loop is a well-defined arch-like structure in the Sun's Stellar atmosphere, atmosphere made up of relatively dense Plasma (physics), plasma confined and isolated from the surrounding medium by magnetic flux tubes. Co ...
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Coronal mass ejection
A coronal mass ejection (CME) is a significant ejection of plasma mass from the Sun's corona into the heliosphere. CMEs are often associated with solar flares and other forms of solar activity, but a broadly accepted theoretical understandin ...
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Solar prominence
In solar physics, a prominence, sometimes referred to as a filament, is a large Plasma (physics), plasma and magnetic field structure extending outward from the Sun's surface, often in a loop shape. Prominences are anchored to the Sun's surface ...
Solar cycle
The Solar cycle, also known as the solar magnetic activity cycle, sunspot cycle, or Schwabe cycle, is a periodic 11-year change in the Sun's activity measured in terms of Modern Maximum, variations in the number of observed sunspots on the Sun ...
Solar maximum
Solar maximum is the regular period of greatest solar activity during the Sun's 11-year solar cycle. During solar maximum, large numbers of sunspots appear, and the solar irradiance output grows by about 0.07%. On average, the solar cycle take ...
Solar flare
A solar flare is a relatively intense, localized emission of electromagnetic radiation in the Sun's atmosphere. Flares occur in active regions and are often, but not always, accompanied by coronal mass ejections, solar particle events, and ot ...
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Helioseismology
Helioseismology is the study of the structure and dynamics of the Sun through its oscillations. These are principally caused by sound waves that are continuously driven and damped by convection near the Sun's surface. It is similar to geoseismol ...
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Heliosphere
The heliosphere is the magnetosphere, astrosphere, and outermost atmospheric layer of the Sun. It takes the shape of a vast, tailed bubble-like region of space. In plasma physics terms, it is the cavity formed by the Sun in the surrounding ...
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Solar wind
The solar wind is a stream of charged particles released from the Sun's outermost atmospheric layer, the Stellar corona, corona. This Plasma (physics), plasma mostly consists of electrons, protons and alpha particles with kinetic energy betwee ...
Bow shock
In astrophysics, bow shocks are shock waves in regions where the conditions of density and pressure change dramatically due to blowing stellar wind. Bow shock occurs when the magnetosphere of an astrophysical object interacts with the nearby fl ...
* Related phenomena
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Solar dynamo
The solar dynamo is a physical process that generates the Sun's magnetic field. It is explained with a variant of the dynamo theory. A naturally occurring electric generator in the Sun's interior produces electric currents and a magnetic field, ...
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Solar eclipse
A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring the view of the Sun from a small part of Earth, totally or partially. Such an alignment occurs approximately every six months, during the eclipse season i ...
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Sunlight
Sunlight is the portion of the electromagnetic radiation which is emitted by the Sun (i.e. solar radiation) and received by the Earth, in particular the visible spectrum, visible light perceptible to the human eye as well as invisible infrare ...
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Solar energy
Solar energy is the radiant energy from the Sun's sunlight, light and heat, which can be harnessed using a range of technologies such as solar electricity, solar thermal energy (including solar water heating) and solar architecture. It is a ...
* Equipment used to study the Sun
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Solar telescope
A solar telescope or a solar observatory is a special-purpose telescope used to observe the Sun. Solar telescopes usually detect light with wavelengths in, or not far outside, the visible spectrum. Obsolete names for Sun telescopes include helio ...
Planets
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Planet
A planet is a large, Hydrostatic equilibrium, rounded Astronomical object, astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets b ...
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Natural satellite
A natural satellite is, in the most common usage, an astronomical body that orbits a planet, dwarf planet, or small Solar System body (or sometimes another natural satellite). Natural satellites are colloquially referred to as moons, a deriv ...
Venus
Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" planet for having almost the same size and mass, and the closest orbit to Earth's. While both are rocky planets, Venus has an atmosphere much thicker ...
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Earth
Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...
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Moon
The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...
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Mars
Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmosph ...
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Moons of Mars
The two natural satellite, moons of Mars (planet), Mars are Phobos (moon), Phobos and Deimos (moon), Deimos. They are irregular in shape. Both were discovered by American astronomer Asaph Hall in August 1877 and are named after the Greek mytholo ...
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Jupiter
Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...
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Moons of Jupiter
There are 97 Natural satellite, moons of Jupiter with confirmed orbits . This number does not include a number of meter-sized moonlets thought to be shed from the inner moons, nor hundreds of possible kilometer-sized outer irregular moons that ...
Saturn
Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth the average density of Earth, but is over 95 tim ...
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Moons of Saturn
The moons of Saturn are numerous and diverse, ranging from tiny moonlets only tens of meters across to the enormous Titan (moon), Titan, which is larger than the planet Mercury (planet), Mercury. There are 274 natural satellite, moons with con ...
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Rings of Saturn
Saturn has the most extensive and complex ring system of any planet in the Solar System. The rings consist of particles in orbit around the planet made almost entirely of water ice, with a trace component of Rock (geology), rocky material. Parti ...
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Uranus
Uranus is the seventh planet from the Sun. It is a gaseous cyan-coloured ice giant. Most of the planet is made of water, ammonia, and methane in a Supercritical fluid, supercritical phase of matter, which astronomy calls "ice" or Volatile ( ...
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Moons of Uranus
Uranus, the seventh planet of the Solar System, has 28 confirmed moons. The 27 with names are named after characters that appear in, or are mentioned in, William Shakespeare's plays and Alexander Pope's poem '' The Rape of the Lock''. Uranus's ...
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Rings of Uranus
The rings of Uranus consists of 13 planetary rings. They are intermediate in complexity between the more extensive set around Saturn and the simpler systems around Jupiter and Neptune. The rings of Uranus were discovered on March 10, 1977, by J ...
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Neptune
Neptune is the eighth and farthest known planet from the Sun. It is the List of Solar System objects by size, fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 t ...
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Moons of Neptune
The planet Neptune has 16 known natural satellite, moons, which are named for minor List of water deities, water deities and a Hippocampus (mythology), water creature in Greek mythology.This is a IAU guideline that will be followed at the naming ...
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Rings of Neptune
The rings of Neptune consist primarily of five principal Planetary ring, rings. They were first discovered (as "arcs") by simultaneous observations of a stellar occultation on 22 July 1984 by André Brahic's and William B. Hubbard's teams at La S ...
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Dwarf planet
A dwarf planet is a small planetary-mass object that is in direct orbit around the Sun, massive enough to be hydrostatic equilibrium, gravitationally rounded, but insufficient to achieve clearing the neighbourhood, orbital dominance like the ...
Pluto
Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of Trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Su ...
Haumea
Haumea ( minor-planet designation: 136108 Haumea) is a dwarf planet located beyond Neptune's orbit. It was discovered in 2004 by a team headed by Mike Brown of Caltech at the Palomar Observatory, and formally announced in 2005 by a team heade ...
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Moons of Haumea
The dwarf planet Haumea has two known moons, Hiiaka and Namaka, named after Hawaiian goddesses. These small moons were discovered in 2005, from observations of Haumea made at the large telescopes of the W. M. Keck Observatory in Hawaii.
H ...
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Makemake
Makemake ( minor-planet designation: 136472 Makemake) is a dwarf planet and the largest of what is known as the classical population of Kuiper belt objects, with a diameter approximately that of Saturn's moon Iapetus, or 60% that of Pluto. It ...
Small Solar System body
A small Solar System body (SSSB) is an object in the Solar System that is neither a planet, a dwarf planet, nor a natural satellite. The term was first defined in 2006 by the International Astronomical Union (IAU) as follows: "All other objects ...
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Asteroid
An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...
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Minor planets
According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...
Vulcanoid asteroid
The vulcanoids are a List of hypothetical Solar System objects, hypothetical population of asteroids that orbit the Sun in a dynamically stable zone inside the orbit of the planet Mercury (planet), Mercury. They are named after the hypothetical p ...
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Near-Earth asteroid
A near-Earth object (NEO) is any small Solar System body orbiting the Sun whose closest approach to the Sun (perihelion) is less than 1.3 times the Earth–Sun distance (astronomical unit, AU). This definition applies to the object's orbit aro ...
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Asteroid belt
The asteroid belt is a torus-shaped region in the Solar System, centered on the Sun and roughly spanning the space between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies called asteroids ...
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Trojan asteroid
In astronomy, a trojan is a small celestial body (mostly asteroids) that shares the orbit of a larger body, remaining in a stable orbit approximately 60° ahead of or behind the main body near one of its Lagrangian points and . Trojans can shar ...
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Centaur
A centaur ( ; ; ), occasionally hippocentaur, also called Ixionidae (), is a creature from Greek mythology with the upper body of a human and the lower body and legs of a horse that was said to live in the mountains of Thessaly. In one version o ...
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Neptune Trojan
Neptune trojans are bodies that orbit the Sun near one of the stable Lagrangian points of Neptune, similar to the trojans of other planets. They therefore have approximately the same orbital period as Neptune and follow roughly the same orbita ...
Meteoroids
A meteoroid ( ) is a small rocky or metallic body in outer space.
Meteoroids are distinguished as objects significantly smaller than ''asteroids'', ranging in size from grains to objects up to wide. Objects smaller than meteoroids are classifie ...
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2 Pallas
Pallas (minor-planet designation: 2 Pallas) is the List of largest asteroids, third-largest asteroid in the Solar System by volume and mass. It is the second asteroid to have been discovered, after 1 Ceres, Ceres, and is likely a remnant ...
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3 Juno
Juno (minor-planet designation: 3 Juno) is a large asteroid in the asteroid belt. Juno was the third asteroid discovered, in 1804, by German astronomer Karl Harding. It is tied with three other asteroids as the thirteenth largest asteroid, and ...
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4 Vesta
Vesta (minor-planet designation: 4 Vesta) is one of the largest objects in the asteroid belt, with a mean diameter of . It was discovered by the German astronomer Heinrich Wilhelm Matthias Olbers on 29 March 1807 and is named after Vesta (mytho ...
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10 Hygiea
10 Hygiea is a large asteroid located in the outer main asteroid belt between the orbits of Mars and Jupiter. It was the tenth known asteroid, discovered on 12 April 1849 by Italian astronomer Annibale de Gasparis at the Astronomical Observa ...
Trans-Neptunian object
A trans-Neptunian object (TNO), also written transneptunian object, is any minor planet in the Solar System that orbits the Sun at a greater average distance than Neptune, which has an orbital semi-major axis of 30.1 astronomical units (AU).
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Kuiper belt
The Kuiper belt ( ) is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 times ...
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Plutino
In astronomy, the plutinos are a dynamical group of trans-Neptunian objects that orbit in 2:3 mean-motion resonance with Neptune. This means that for every two orbits a plutino makes, Neptune orbits three times. The dwarf planet Pluto is the la ...
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90482 Orcus
Orcus (minor-planet designation: 90482 Orcus) is a dwarf planet located in the Kuiper belt, with one large moon, Vanth. It has an estimated diameter of , comparable to the Inner Solar System dwarf planet Ceres. The surface of Orcus is relativ ...
Cubewano
A classical Kuiper belt object, also called a cubewano ( "QB1-o"), is a low-eccentricity Kuiper belt object (KBO) that orbits beyond Neptune and is not controlled by an orbital resonance with Neptune. Cubewanos have orbits with semi-major axe ...
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20000 Varuna
20000 Varuna (provisional designation ) is a large trans-Neptunian object in the Kuiper belt. It was discovered in November 2000 by American astronomer Robert McMillan during a Spacewatch survey at the Kitt Peak National Observatory. It is na ...
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50000 Quaoar
Quaoar ( minor-planet designation: 50000 Quaoar) is a ringed dwarf planet in the Kuiper Belt, a ring of many icy planetesimals beyond Neptune. It has an elongated ellipsoidal shape with an average diameter of , about half the size of the d ...
Scattered disc
The scattered disc (or scattered disk) is a distant circumstellar disc in the Solar System that is sparsely populated by icy small Solar System bodies, which are a subset of the broader family of trans-Neptunian objects. The scattered-disc obj ...
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90377 Sedna
Sedna ( minor-planet designation: 90377 Sedna) is a dwarf planet in the outermost reaches of the Solar System, orbiting the Sun far beyond the orbit of Neptune. Discovered in 2003, the frigid planetoid is one of the reddest known among Solar ...
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Comet
A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...
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List of periodic comets
Periodic comets (also known as short-period comets) are comets with orbital periods of less than 200 years or that have been observed during more than a single perihelion passage (e.g. 153P/Ikeya–Zhang). "Periodic comet" is also sometimes us ...
Oort cloud
The Oort cloud (pronounced or ), sometimes called the Öpik–Oort cloud, is scientific theory, theorized to be a cloud of billions of Volatile (astrogeology), icy planetesimals surrounding the Sun at distances ranging from 2,000 to 200,000 A ...
Exoplanets
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Exoplanet
An exoplanet or extrasolar planet is a planet outside the Solar System. The first confirmed detection of an exoplanet was in 1992 around a pulsar, and the first detection around a main-sequence star was in 1995. A different planet, first det ...
(also known as extrasolar planets) – planet outside the Solar System. A total of 4,341 such planets have been identified as of 28 Jan 2021.
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Super-Earth
A super-Earth is a type of exoplanet with a mass higher than Earth, but substantially below those of the Solar System's ice giants, Uranus and Neptune, which are 14.5 and 17.1 times Earth's, respectively.
The term "super-Earth" refers only to t ...
– exoplanet with a mass higher than Earth's, but substantially below those of the Solar System's
ice giant
An ice giant is a giant planet composed mainly of elements heavier than hydrogen and helium, such as oxygen, carbon, nitrogen, and sulfur. There are two ice giants in the Solar System: Uranus and Neptune.
In astrophysics and planetary science ...
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Mini-Neptune
A Mini-Neptune (sometimes known as a gas dwarf or transitional planet) is a planet less massive than Neptune but resembling Neptune in that it has a thick hydrogen-helium atmosphere, probably with deep layers of ice, rock or liquid oceans (made o ...
– also known as a gas dwarf or transitional planet. A planet up to 10 Earth masses, but less massive than Uranus and Neptune.
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Super-Jupiter
A super-Jupiter is a gas giant exoplanet that is more massive than the planet Jupiter. For example, substellar companion, companions at the planet–brown dwarf borderline have been called super-Jupiters, such as around the star Kappa Andromedae. ...
– an exoplanet more massive than
Jupiter
Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...
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Sub-Earth
A sub-Earth is a planet "substantially less massive" than Earth and Venus. In the Solar System, this category includes Mercury (planet), Mercury and Mars.
Characteristics
Sub-Earth exoplanets are among the most difficult type to detect becau ...
– an exoplanet "substantially less massive" than Earth and
Venus
Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" planet for having almost the same size and mass, and the closest orbit to Earth's. While both are rocky planets, Venus has an atmosphere much thicker ...
Hot Jupiter
Hot Jupiters (sometimes called hot Saturns) are a class of gas giant exoplanets that are inferred to be physically similar to Jupiter (i.e. Jupiter analogue, Jupiter analogues) but that have very short orbital periods (). The close proximity to t ...
– an exoplanet whose characteristics are similar to Jupiter, but that have high surface temperatures because they orbit very close to their parent stars, whereas Jupiter orbits its parent star (the
Sun
The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...
) at 5.2 AU (780×106 km), causing low surface temperatures.
** Hot Neptune – an exoplanet in an orbit close to its star (normally less than one astronomical unit away), with a mass similar to that of Uranus or Neptune.
** Pulsar planet – a planet that orbits a pulsar or a rapidly rotating neutron star.
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Rogue planet
A rogue planet, also termed a free-floating planet (FFP) or an isolated planetary-mass object (iPMO), is an interstellar object of planetary mass which is not gravitationally bound to any star or brown dwarf.
Rogue planets may originate from ...
(also known as an interstellar planet) – a planetary-mass object that orbits the galaxy directly.
Stars and stellar objects
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Fixed stars
In astronomy, the fixed stars () are the luminary points, mainly stars, that appear not to move relative to one another against the darkness of the night sky in the background. This is in contrast to those lights visible to the naked eye, name ...
Stars
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Stellar evolution
Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is consi ...
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Star formation
Star formation is the process by which dense regions within molecular clouds in interstellar space—sometimes referred to as "stellar nurseries" or "star-forming regions"—Jeans instability, collapse and form stars. As a branch of astronomy, sta ...
Main sequence
In astronomy, the main sequence is a classification of stars which appear on plots of stellar color index, color versus absolute magnitude, brightness as a continuous and distinctive band. Stars on this band are known as main-sequence stars or d ...
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Horizontal branch
The horizontal branch (HB) is a stage of stellar evolution that immediately follows the red-giant branch in stars whose masses are similar to the Sun's. Horizontal-branch stars are powered by helium fusion in the core (via the triple-alpha proc ...
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Asymptotic giant branch
The asymptotic giant branch (AGB) is a region of the Hertzsprung–Russell diagram populated by evolved cool luminous stars. This is a period of stellar evolution undertaken by all low- to intermediate-mass stars (about 0.5 to 8 solar masses) lat ...
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Dredge-up
A dredge-up is any one of several stages in the evolution of some stars. By definition, during a ''dredge-up'', a convection zone extends all the way from the star's surface down to the layers of material that have undergone fusion. Consequently, ...
Mira variable
Mira variables (named for the prototype star Mira) are a class of pulsating stars characterized by very red colours, pulsation periods longer than 100 days, and amplitudes greater than one magnitude in infrared and 2.5 magnitude at visual wave ...
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Planetary nebula
A planetary nebula is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives.
The term "planetary nebula" is a misnomer because they are unrelated to planets. The ...
Luminous blue variable
Luminous blue variables (LBVs) are rare, massive, evolved stars that show unpredictable and sometimes dramatic variations in their spectra and brightness. They are also known as S Doradus variables after S Doradus, one of the brightest stars of th ...
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Wolf–Rayet star
Wolf–Rayet stars, often abbreviated as WR stars, are a rare heterogeneous set of stars with unusual spectroscopy, spectra showing prominent broad emission lines of ionised helium and highly ionised nitrogen or carbon. The spectra indicate very ...
Supernova
A supernova (: supernovae or supernovas) is a powerful and luminous explosion of a star. A supernova occurs during the last stellar evolution, evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion ...
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Hypernova
A hypernova is a very energetic supernova which is believed to result from an extreme core collapse scenario. In this case, a massive star (>30 solar masses) collapses to form a rotating black hole emitting twin astrophysical jets and surrounded b ...
Protostar
A protostar is a very young star that is still gathering mass from its parent molecular cloud. It is the earliest phase in the process of stellar evolution. For a low-mass star (i.e. that of the Sun or lower), it lasts about 500,000 years. The p ...
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Molecular cloud
A molecular cloud—sometimes called a stellar nursery if star formation is occurring within—is a type of interstellar cloud of which the density and size permit absorption nebulae, the formation of molecules (most commonly molecular hydrogen, ...
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H II region
An H II region is a region of interstellar atomic hydrogen that is ionized. It is typically in a molecular cloud of partially ionized gas in which star formation has recently taken place, with a size ranging from one to hundreds of light year ...
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Bok globule
In astronomy, Bok globules are isolated and relatively small dark nebulae containing dense cosmic dust and gas from which star formation may take place. Bok globules are found within H II regions, and typically have a mass of about two to 50 sol ...
Herbig–Haro object
Herbig–Haro (HH) objects are bright patches of nebula, nebulosity associated with newborn stars. They are formed when narrow jets of partially plasma (physics), ionised gas ejected by stars collide with nearby clouds of gas and dust at several ...
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Hayashi track
The Hayashi track is a luminosity–temperature relationship obeyed by infant stars of less than in the pre-main-sequence phase (PMS phase) of stellar evolution. It is named after Japanese astrophysicist Chushiro Hayashi. On the Hertzsprung� ...
T Tauri star
T Tauri stars (TTS) are a class of variable stars that are less than about ten million years old. This class is named after the prototype, T Tauri, a young star in the Taurus Molecular Cloud, Taurus star-forming region. They are found near mo ...
Dwarf star
A dwarf star is a star of relatively small size and low luminosity. Most main sequence stars are dwarf stars. The meaning of the word "dwarf" was later extended to some star-sized objects that are not stars, and compact stellar remnants that are ...
Red dwarf
A red dwarf is the smallest kind of star on the main sequence. Red dwarfs are by far the most common type of fusing star in the Milky Way, at least in the neighborhood of the Sun. However, due to their low luminosity, individual red dwarfs are ...
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Subgiant
A subgiant is a star that is brighter than a normal main-sequence star of the same spectral class, but not as bright as giant stars. The term subgiant is applied both to a particular spectral luminosity class and to a stage in the evolution ...
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Giant star
A giant star has a substantially larger radius and luminosity than a main-sequence (or ''dwarf'') star of the same surface temperature. They lie above the main sequence (luminosity class V in the Yerkes spectral classification) on the Hertzsp ...
Red giant
A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses ()) in a late phase of stellar evolution. The stellar atmosphere, outer atmosphere is inflated and tenuous, making the radius large and the surface t ...
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Bright giant
A giant star has a substantially larger radius and luminosity than a main-sequence (or ''dwarf'') star of the same surface temperature. They lie above the main sequence (luminosity class V in the Yerkes spectral classification) on the Hertzspr ...
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Supergiant
Supergiants are among the most massive and most luminous stars. Supergiant stars occupy the top region of the Hertzsprung–Russell diagram, with absolute visual magnitudes between about −3 and −8. The temperatures of supergiant stars range ...
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Blue supergiant
A blue supergiant (BSG) is a hot, luminous star, often referred to as an OB supergiant. They are usually considered to be those with luminosity class I and spectral class B9 or earlier, although sometimes A-class supergiants are also deemed blu ...
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Red supergiant
Red supergiants (RSGs) are stars with a supergiant luminosity class ( Yerkes class I) and a stellar classification K or M. They are the largest stars in the universe in terms of volume, although they are not the most massive or luminous. Betelg ...
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Yellow supergiant
A yellow supergiant (YSG) is a star, generally of spectral type F or G, having a supergiant luminosity class (e.g. Ia or Ib). They are stars that have evolved away from the main sequence, expanding and becoming more luminous.
Yellow supergiants ...
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Hypergiant
A hypergiant ( luminosity class 0 or Ia+) is a very rare type of star that has an extremely high luminosity, mass, size and mass loss because of its extreme stellar winds. The term ''hypergiant'' is defined as luminosity class 0 (zero) in the MK ...
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Yellow hypergiant
A yellow hypergiant (YHG) is a massive star with an extended atmosphere, a spectral class from A to K, and, starting with an initial mass of about 20–60 solar masses, has lost as much as half that mass. They are amongst the most visually lumino ...
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Blue straggler
A blue straggler is a type of star that is more luminous and bluer than expected. Typically identified in a stellar cluster, they have a higher effective temperature than the main sequence turnoff point for the cluster, where ordinary stars b ...
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Stellar classification
In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction gratin ...
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O-type main-sequence star
An O-type main-sequence star (O V) is a main-sequence (core hydrogen-burning) star of spectral type O and luminosity class V. These stars have between 15 and 90 times the mass of the Sun and surface temperatures between 30,000 and 50,000 K. Th ...
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B-type main-sequence star
A B-type main-sequence star (B V) is a main-sequence (hydrogen-burning) star of spectral type B and luminosity class V. These stars have from 2 to 16 times the mass of the Sun and surface temperatures between 10,000 and 30,000 K. B-type stars ...
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A-type main-sequence star
An A-type main-sequence star (A) or A dwarf star is a main-sequence (hydrogen burning) star of spectral type A and luminosity class (five). These stars have spectra defined by strong hydrogen Balmer absorption lines. They measure between 1 ...
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F-type main-sequence star
An F-type main-sequence star (F V) is a main-sequence, hydrogen-fusing star of spectral type F and luminosity class V. These stars have from 1.0 to 1.4 times the mass of the Sun and surface temperatures between 6,000 and 7,600 K.Tables ...
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G-type main-sequence star
A G-type main-sequence star (spectral type: G-V), also often, and imprecisely, called a yellow dwarf, or G star, is a main sequence, main-sequence star (luminosity class V) of stellar classification, spectral type G. Such a star has about 0.9 to ...
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K-type main-sequence star
A K-type main-sequence star, also referred to as a K-type dwarf, or orange dwarf, is a main-sequence (hydrogen-burning) star of spectral type K and luminosity class V. These stars are intermediate in size between red M-type main-sequence stars ...
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M-type main-sequence star
A red dwarf is the smallest kind of star on the main sequence. Red dwarfs are by far the most common type of fusing star in the Milky Way, at least in the neighborhood of the Sun. However, due to their low luminosity, individual red dwarfs are ...
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Be star
Be stars are a heterogeneous set of stars with B spectral types and emission lines. A narrower definition, sometimes referred to as ''classical Be stars'', is a non-supergiant B star whose spectrum has, or had at some time, one or more Balmer ...
Subdwarf B star
A B-type subdwarf (sdB) is a kind of subdwarf star with B-type main-sequence star, spectral type B. They differ from the typical subdwarf by being much hotter and brighter. They are situated at the "extreme horizontal branch" of the Hertzsprung� ...
Peculiar star
In astrophysics, chemically peculiar stars (CP stars) are stars with distinctly unusual metal abundances, at least in their surface layers.
Classification
Chemically peculiar stars are common among hot main-sequence (hydrogen-burning) stars. These ...
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Am star
An Am star or metallic-line star is a type of chemically peculiar star of spectral type A whose spectrum has strong and often variable absorption lines of metals such as zinc
Zinc is a chemical element; it has symbol Zn and atomic number 30. ...
Carbon star
A carbon star (C-type star) is typically an asymptotic giant branch star, a luminous red giant, whose Stellar atmosphere, atmosphere contains more carbon than oxygen. The two elements combine in the upper layers of the star, forming carbon monox ...
S-type star
An S-type star (or just S star) is a cool giant star with approximately equal quantities of carbon and oxygen in its atmosphere. The class was originally defined in 1922 by Paul Merrill for stars with unusual absorption lines and molecular bands ...
White dwarf
A white dwarf is a Compact star, stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very density, dense: in an Earth sized volume, it packs a mass that is comparable to the Sun. No nuclear fusion takes place i ...
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Black dwarf
A black dwarf is a theoretical stellar remnant, specifically a white dwarf that has cooled sufficiently to no longer emit significant heat or light. Because the time required for a white dwarf to reach this state is calculated to be longer than ...
Neutron star
A neutron star is the gravitationally collapsed Stellar core, core of a massive supergiant star. It results from the supernova explosion of a stellar evolution#Massive star, massive star—combined with gravitational collapse—that compresses ...
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Pulsar
A pulsar (''pulsating star, on the model of quasar'') is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its Poles of astronomical bodies#Magnetic poles, magnetic poles. This radiation can be obse ...
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Magnetar
A magnetar is a type of neutron star with an extremely powerful magnetic field (~109 to 1011 T, ~1013 to 1015 G). The magnetic-field decay powers the emission of high-energy electromagnetic radiation, particularly X-rays and gamma rays.Ward; Br ...
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Stellar black hole
A stellar black hole (or stellar-mass black hole) is a black hole formed by the gravitational collapse of a star. They have masses ranging from about 5 to several tens of solar masses. They are the remnants of supernova explosions, which may be ...
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Compact star
In astronomy, the term compact object (or compact star) refers collectively to white dwarfs, neutron stars, and black holes. It could also include exotic stars if such hypothetical, dense bodies are confirmed to exist. All compact objects have a ...
Substellar object
A substellar object, sometimes called a substar, is an astronomical object, the mass of which is smaller than the smallest mass at which hydrogen fusion can be sustained (approximately 0.08 solar masses). This definition includes brown dwarfs and f ...
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Brown dwarf
Brown dwarfs are substellar objects that have more mass than the biggest gas giant planets, but less than the least massive main sequence, main-sequence stars. Their mass is approximately 13 to 80 Jupiter mass, times that of Jupiter ()not big en ...
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Sub-brown dwarf
A sub-brown dwarf or planetary-mass brown dwarf is an astronomical object that formed in the same manner as stars and brown dwarfs (i.e. through the collapse of a gas cloud) but that has a planetary mass, therefore by definition below the limi ...
Thorne–Żytkow object
A Thorne–Żytkow object (TŻO or TZO), a type of hybrid star, is a conjectured type of star wherein a red giant or Red supergiant star, red supergiant contains a neutron star at its core, formed from the Stellar collision, collision of the gian ...
Stellar nucleosynthesis
In astrophysics, stellar nucleosynthesis is the creation of chemical elements by nuclear fusion reactions within stars. Stellar nucleosynthesis has occurred since the original creation of hydrogen, helium and lithium during the Big Bang. As a ...
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Alpha process
The alpha process, also known as alpha capture or the alpha ladder, is one of two classes of nuclear fusion reactions by which stars convert helium into heavier elements. The other class is a cycle of reactions called the triple-alpha process, w ...
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Triple-alpha process
The triple-alpha process is a set of nuclear fusion reactions by which three helium-4 nuclei (alpha particles) are transformed into carbon.
In stars
Helium accumulates in the cores of stars as a result of the proton–proton chain reaction a ...
Helium flash
A helium flash is a very brief thermal runaway nuclear fusion of large quantities of helium into carbon through the triple-alpha process in the core of low-mass stars (between 0.5-0.44 solar masses () and 2.0 ) during their red giant phase. The Su ...
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CNO cycle
In astrophysics, the carbon–nitrogen–oxygen (CNO) cycle, sometimes called Bethe–Weizsäcker cycle, after Hans Albrecht Bethe and Carl Friedrich von Weizsäcker, is one of the two known sets of fusion reactions by which stars convert h ...
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Lithium burning
Lithium burning is a nucleosynthetic process in which lithium is depleted in a star. Lithium is generally present in brown dwarfs and not in older low-mass stars. Stars, which by definition must achieve the high temperature (2.5 million K) neces ...
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Carbon-burning process
The carbon-burning process or carbon fusion is a set of nuclear fusion reactions that take place in the cores of massive stars (at least 4 \beginM_\odot\end at birth) that combines carbon into other elements. It requires high temperatures (> 5&t ...
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Neon-burning process
The neon-burning process is a set of nuclear fusion reactions that take place in evolved massive stars with at least 8 Solar masses. Neon burning requires high temperatures and densities (around 1.2 billion K or 100 keV and 4 billion kg/m3).
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Silicon-burning process
In astrophysics, silicon burning is a very brief sequence of nuclear fusion reactions that occur in massive stars with a minimum of about 8–11 solar masses. Silicon burning is the final stage of fusion for massive stars that have run out of the f ...
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S-process
The slow neutron-capture process, or ''s''-process, is a series of nuclear reactions, reactions in nuclear astrophysics that occur in stars, particularly asymptotic giant branch stars. The ''s''-process is responsible for the creation (nucleosynt ...
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R-process
In nuclear astrophysics, the rapid neutron-capture process, also known as the ''r''-process, is a set of nuclear reactions that is responsible for nucleosynthesis, the creation of approximately half of the Atomic nucleus, atomic nuclei Heavy meta ...
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Nova
A nova ( novae or novas) is a transient astronomical event that causes the sudden appearance of a bright, apparently "new" star (hence the name "nova", Latin for "new") that slowly fades over weeks or months. All observed novae involve white ...
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Nova remnant
A nova remnant is made up of the material either left behind by a sudden explosive fusion eruption by classical novae, or from multiple ejections by recurrent novae. Over their short lifetimes, nova shells show expansion velocities of around 1000& ...
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Stellar structure
Stellar structure models describe the internal structure of a star in detail and make predictions about the luminosity, the color and the future evolution of the star. Different classes and ages of stars have different internal structures, refle ...
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Solar core
The core of the Sun is considered to extend from the center to about 0.2 of the solar radius (). It is the hottest part of the Sun and of the Solar System. It has a density of at the center, and a temperature of 15 million kelvins (15 million de ...
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Convection zone
A convection zone, convective zone or convective region of a star is a layer which is unstable due to convection. Energy is primarily or partially transported by convection in such a region. In a radiation zone, energy is transported by radiation ...
Solar-like oscillations
Solar-like oscillations are oscillations in star
A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many ot ...
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Radiation zone
A radiative zone is a layer of a star's interior where energy is primarily transported toward the exterior by means of radiative diffusion and thermal conduction, rather than by convection. Energy travels through the radiative zone in the form of ...
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Photosphere
The photosphere is a star's outer shell from which light is radiated. It extends into a star's surface until the plasma becomes opaque, equivalent to an optical depth of approximately , or equivalently, a depth from which 50% of light will esc ...
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Starspot
Starspots are stellar phenomena, so-named by analogy with sunspots.
Spots as small as sunspots have not been detected on other stars, as they would cause undetectably small fluctuations in brightness. The commonly observed starspots are in gene ...
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Chromosphere
A chromosphere ("sphere of color", from the Ancient Greek words χρῶμα (''khrôma'') 'color' and σφαῖρα (''sphaîra'') 'sphere') is the second layer of a Stellar atmosphere, star's atmosphere, located above the photosphere and below t ...
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Stellar corona
In astronomy, a corona (: coronas or coronae) is the outermost layer of a star's Stellar atmosphere, atmosphere. It is a hot but relatively luminosity, dim region of Plasma (physics), plasma populated by intermittent coronal structures such as so ...
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Stellar wind
A stellar wind is a flow of gas ejected from the stellar atmosphere, upper atmosphere of a star. It is distinguished from the bipolar outflows characteristic of young stars by being less collimated, although stellar winds are not generally spheri ...
Asteroseismology
Asteroseismology is the study of oscillations in stars. Stars have many Resonance, resonant modes and frequencies, and the path of sound waves passing through a star depends on the local speed of sound, which in turn depends on local temperature a ...
Kelvin–Helmholtz mechanism
The Kelvin–Helmholtz mechanism is an astronomical process that occurs when the surface of a star or a planet cools. The cooling causes the internal pressure to drop, and the star or planet shrinks as a result. This compression, in turn, heats t ...
Stellar dynamics
Stellar dynamics is the branch of astrophysics which describes in a statistical way the collective motions of stars subject to their mutual gravity. The essential difference from celestial mechanics is that the number of body N \gg 10.
Typic ...
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Effective temperature
The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature ...
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Stellar kinematics
In astronomy, stellar kinematics is the observational study or measurement of the kinematics or motions of stars through space.
Stellar kinematics encompasses the measurement of stellar velocities in the Milky Way and its satellites as well as ...
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Stellar magnetic field
A stellar magnetic field is a magnetic field generated by the motion of conductive plasma inside a star. This motion is created through convection, which is a form of energy transport involving the physical movement of material. A localized mag ...
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Magnitude
Magnitude may refer to:
Mathematics
*Euclidean vector, a quantity defined by both its magnitude and its direction
*Magnitude (mathematics), the relative size of an object
*Norm (mathematics), a term for the size or length of a vector
*Order of ...
Solar mass
The solar mass () is a frequently used unit of mass in astronomy, equal to approximately . It is approximately equal to the mass of the Sun. It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxie ...
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Metallicity
In astronomy, metallicity is the Abundance of the chemical elements, abundance of Chemical element, elements present in an object that are heavier than hydrogen and helium. Most of the normal currently detectable (i.e. non-Dark matter, dark) matt ...
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Stellar rotation
Stellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surface.
The rotation of a star produces an equatorial bu ...
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UBV photometric system
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The UBV photometric system (from ''Ultraviolet, Blue, Visual''), also called the Johnson system (or Johnson-Morgan system), is a photometric system usually employed for classifying stars according to their colors.
It was the first stan ...
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Variable star
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes systematically with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are ...
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Star system
A star system or stellar system is a small number of stars that orbit each other, bound by gravity, gravitational attraction. It may sometimes be used to refer to a single star. A large group of stars bound by gravitation is generally calle ...
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Binary star
A binary star or binary star system is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved as separate stars us ...
Common envelope
In astronomy, a common envelope (CE) is gas that contains a binary star system. The gas does not rotate at the same rate as the embedded binary system. A system with such a configuration is said to be in a common envelope phase or undergoing comm ...
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Multiple star
A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction. It may sometimes be used to refer to a single star. A large group of stars bound by gravitation is generally called a ''st ...
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Accretion disc
An accretion disk is a structure (often a circumstellar disk) formed by diffuse material in orbital motion around a massive central body. The central body is most frequently a star. Friction, uneven irradiance, magnetohydrodynamic effects, and ...
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Planetary system
A planetary system is a set of gravity, gravitationally bound non-stellar Astronomical object, bodies in or out of orbit around a star or star system. Generally speaking, systems with one or more planets constitute a planetary system, although ...
Pole star
A pole star is a visible star that is approximately aligned with the axis of rotation of an astronomical body; that is, a star whose apparent position is close to one of the celestial poles. On Earth, a pole star would lie directly overhead when ...
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Circumpolar star
A circumpolar star is a star that, as viewed from a given latitude on Earth, never sets below the horizon due to its apparent proximity to one of the celestial poles. Circumpolar stars are therefore visible from said location toward the nearest p ...
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Magnitude
Magnitude may refer to:
Mathematics
*Euclidean vector, a quantity defined by both its magnitude and its direction
*Magnitude (mathematics), the relative size of an object
*Norm (mathematics), a term for the size or length of a vector
*Order of ...
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Apparent magnitude
Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...
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Photographic magnitude
Photographic magnitude ( or ) is a measure of the relative brightness of a star or other astronomical object as imaged on a photographic film emulsion with a camera attached to a telescope. An object's apparent photographic magnitude depends o ...
Radial velocity
The radial velocity or line-of-sight velocity of a target with respect to an observer is the rate of change of the vector displacement between the two points. It is formulated as the vector projection of the target-observer relative velocity ...
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Proper motion
Proper motion is the astrometric measure of changes in the apparent places of stars or other celestial objects as they move relative to the center of mass of the Solar System. It is measured relative to the distant stars or a stable referenc ...
Lists of stars
The following are lists of stars. Stars are astronomical objects that spend some portion of their existence generating energy through thermonuclear fusion.
By location
* Lists of stars by constellation
By name
* List of proper names of stars
* ...
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List of proper names of stars
These names of stars that have either been approved by the International Astronomical Union or which have been in somewhat recent use. IAU approval comes mostly from its Working Group on Star Names, which has been publishing a "List of IAU-approve ...
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List of Arabic star names
This is a list of Arabic star names. In Western astronomy, most of the accepted star names are Arabic, a few are Greek language, Greek and some are of unknown origin. Typically only bright stars have names.
History of Arabic star names
Very ol ...
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Traditional Chinese star names
Chinese star names (Chinese language, Chinese: , ''xīng míng'') are named according to ancient Chinese astronomy and Chinese astrology, astrology. The sky is divided into Chinese constellations, star mansions (, ''xīng xiù'', also translated a ...
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List of most massive stars
This is a list of the most massive stars that have been discovered, in solar mass units ().
Uncertainties and caveats
Most of the masses listed below are contested and, being the subject of current research, remain under review and subject to con ...
List of largest known stars
A list is a set of discrete items of information collected and set forth in some format for utility, entertainment, or other purposes. A list may be memorialized in any number of ways, including existing only in the mind of the list-maker, but ...
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List of brightest stars
This is a list of stars arranged by their apparent magnitude – their brightness as observed from Earth. It includes all stars brighter than magnitude +2.50 in visible light, measured using a ''V''-band filter in the UBV photometric system. St ...
List of most luminous stars
This is a list of stars arranged by their absolute magnitude – their intrinsic stellar luminosity. This cannot be observed directly, so instead must be calculated from the apparent magnitude (the brightness as seen from Earth), the distanc ...
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List of nearest stars
This list covers all known stars, white dwarfs, brown dwarfs, and sub-brown dwarfs within of the Sun. So far, 131 such objects have been found. Only List of nearest bright stars, 22 are bright enough to be visible without a telescope, for whi ...
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List of nearest bright stars
The following nearest bright stars are found within of the closest star, the Sun, and have an absolute magnitude of +8.5 or brighter, which is approximately comparable to a listing of stars more luminous than a red dwarf. Right ascension and ...
List of brown dwarfs
A list is a set of discrete items of information collected and set forth in some format for utility, entertainment, or other purposes. A list may be memorialized in any number of ways, including existing only in the mind of the list-maker, bu ...
Variable star
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes systematically with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are ...
* Pulsating
** Cepheids and cepheid-like
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Cepheid variable
A Cepheid variable () is a type of variable star that pulsates radially, varying in both diameter and temperature. It changes in brightness, with a well-defined stable period (typically 1–100 days) and amplitude. Cepheids are important cosmi ...
RR Lyrae variable
RR Lyrae variables are periodic variable stars, commonly found in globular clusters. They are used as standard candles to measure (extra) galactic distances, assisting with the cosmic distance ladder. This class is named after the prototype a ...
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Delta Scuti variable
A Delta Scuti variable (sometimes termed dwarf cepheid when the V-band amplitude is larger than 0.3 mag.) is a class of pulsating star, comprising several sub-classes of object with A- or F-type spectra.
The variables follow a period-luminosity ...
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SX Phoenicis variable
An SX Phoenicis variable is a type of variable star. These stars exhibit a short period pulsation behavior that varies on time scales of 0.03–0.08 days (0.7–1.9 hours). They have spectral classifications in the range A2-F5 and vary in magnitude ...
Mira variable
Mira variables (named for the prototype star Mira) are a class of pulsating stars characterized by very red colours, pulsation periods longer than 100 days, and amplitudes greater than one magnitude in infrared and 2.5 magnitude at visual wave ...
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Semiregular variable
In astronomy, a semiregular variable star, a type of variable star, is a Red giant, giant or supergiant of intermediate and late (cooler) spectral type. It shows considerable periodicity in its light changes, accompanied or sometimes interrupted b ...
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Slow irregular variable
A slow irregular variable (ascribed the GCVS types L, LB and LC) is a variable star that exhibit no or very poorly defined periodicity in their slowly changing light emissions. These stars have often been little-studied, and once more is learnt a ...
Alpha Cygni variable
Alpha Cygni variables are variable stars which exhibit non-radial pulsations, meaning that some portions of the stellar surface are contracting at the same time other parts expand. They are supergiant
Supergiants are among the most massive and m ...
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Pulsating white dwarf
A pulsating white dwarf is a white dwarf star whose luminosity variable star, varies due to non-radial gravity wave pulsations within itself. Known types of pulsating white dwarfs include DAV, or ZZ Ceti, stars, with hydrogen-dominated atmosphere ...
Main Sequence
In astronomy, the main sequence is a classification of stars which appear on plots of stellar color index, color versus absolute magnitude, brightness as a continuous and distinctive band. Stars on this band are known as main-sequence stars or d ...
Flare star
A flare star is a variable star that can undergo unpredictable dramatic increases in brightness for a few minutes. It is believed that the flares on flare stars are analogous to solar flares in that they are due to magnetic reconnection, the magne ...
** Giants and supergiants
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Luminous blue variable
Luminous blue variables (LBVs) are rare, massive, evolved stars that show unpredictable and sometimes dramatic variations in their spectra and brightness. They are also known as S Doradus variables after S Doradus, one of the brightest stars of th ...
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Gamma Cassiopeiae variable
A Gamma Cassiopeiae variable (γ Cassiopeiae variable) is a type of variable star, named for its prototype γ Cassiopeiae.
Variability
γ Cassiopeiae variables show irregular changes in brightness on a timescale of decades. These typically ha ...
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R Coronae Borealis variable
An R Coronae Borealis variable (abbreviated RCB, R CrB) is an eruptive variable star that varies in luminosity in two modes, one low amplitude pulsation (a few tenths of a magnitude), and one irregular, unpredictably-sudden fading by 1 to 9 magni ...
** Eruptive binary
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RS Canum Venaticorum variable An RS Canum Venaticorum variable is a type of variable star. The variable type consists of close binary stars having active chromospheres which can cause large stellar spots. These spots are believed to cause variations in their observed luminosity. ...
Dwarf nova
A dwarf nova (pl. wiktionary:nova, novae), or U Geminorum variable, is one of several types of cataclysmic variable star, consisting of a close binary star system in which one of the components is a white dwarf that accretion disk, accretes matter ...
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Nova
A nova ( novae or novas) is a transient astronomical event that causes the sudden appearance of a bright, apparently "new" star (hence the name "nova", Latin for "new") that slowly fades over weeks or months. All observed novae involve white ...
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Supernova
A supernova (: supernovae or supernovas) is a powerful and luminous explosion of a star. A supernova occurs during the last stellar evolution, evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion ...
*** Z Andromedae
* Rotating
** Non-spherical
*** Ellipsoidal
** Stellar spots
*** FK Comae Berenices
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BY Draconis variable
BY Draconis variables are variable stars of late spectral types, usually K or M, and typically belong to the main sequence. The name comes from the archetype for this category of variable star system, BY Draconis. They exhibit variations in thei ...
Pulsar
A pulsar (''pulsating star, on the model of quasar'') is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its Poles of astronomical bodies#Magnetic poles, magnetic poles. This radiation can be obse ...
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Eclipsing binary
A binary star or binary star system is a Star system, system of two stars that are gravity, gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved ...
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Algol variable
Algol variables or Algol-type binaries are a class of eclipsing binary stars that are similar to the prototype member of this class, β Persei (Beta Persei, Algol). An Algol binary is a system where both stars are near-spherical such that ...
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Beta Lyrae variable
Beta Lyrae variables are a class of close binary stars. Their total brightness is variable star, variable because the two component stars orbit each other, and in this orbit one component periodically passes in front of the other one, thereby bloc ...
Supernova
A supernova (: supernovae or supernovas) is a powerful and luminous explosion of a star. A supernova occurs during the last stellar evolution, evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion ...
* Classes
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Type Ia supernova
A Type Ia supernova (read: "type one-A") is a type of supernova that occurs in binary systems (two stars orbiting one another) in which one of the stars is a white dwarf. The other star can be anything from a giant star to an even smaller white ...
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Type Ib and Ic supernovae
Type Ib and Type Ic supernovae are categories of supernovae that are caused by the stellar core collapse of massive stars. These stars have shed or been stripped of their outer envelope of hydrogen, and, when compared to the spectru ...
Hypernova
A hypernova is a very energetic supernova which is believed to result from an extreme core collapse scenario. In this case, a massive star (>30 solar masses) collapses to form a rotating black hole emitting twin astrophysical jets and surrounded b ...
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Quark-nova
A quark-nova is the hypothetical violent explosion resulting from the conversion of a neutron star to a quark star. Analogous to a supernova heralding the birth of a neutron star, a quark nova signals the creation of a quark star. The term quark ...
Pair-instability supernova
A pair-instability supernova is a type of supernova predicted to occur when pair production, the production of free electrons and positrons in the collision between atomic nuclei and energetic gamma rays, temporarily reduces the internal radiatio ...
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Supernova nucleosynthesis
Supernova nucleosynthesis is the nucleosynthesis of chemical elements in supernova explosions.
In sufficiently massive stars, the nucleosynthesis by fusion of lighter elements into heavier ones occurs during sequential hydrostatic burning process ...
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P-process
The term p-process (''p'' for proton) is used in two ways in the scientific literature concerning the astrophysical origin of the elements (nucleosynthesis). Originally it referred to a proton capture process which was proposed to be the source ...
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R-process
In nuclear astrophysics, the rapid neutron-capture process, also known as the ''r''-process, is a set of nuclear reactions that is responsible for nucleosynthesis, the creation of approximately half of the Atomic nucleus, atomic nuclei Heavy meta ...
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Gamma-ray burst
In gamma-ray astronomy, gamma-ray bursts (GRBs) are extremely energetic events occurring in distant Galaxy, galaxies which represent the brightest and most powerful class of explosion in the universe. These extreme Electromagnetic radiation, ele ...
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Carbon detonation
Carbon detonation or carbon deflagration is the violent reignition of thermonuclear fusion in a white dwarf star that was previously slowly cooling. It involves a runaway thermonuclear process which spreads through the white dwarf in a matter of s ...
* Progenitors
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Luminous blue variable
Luminous blue variables (LBVs) are rare, massive, evolved stars that show unpredictable and sometimes dramatic variations in their spectra and brightness. They are also known as S Doradus variables after S Doradus, one of the brightest stars of th ...
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Wolf–Rayet star
Wolf–Rayet stars, often abbreviated as WR stars, are a rare heterogeneous set of stars with unusual spectroscopy, spectra showing prominent broad emission lines of ionised helium and highly ionised nitrogen or carbon. The spectra indicate very ...
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Supergiant
Supergiants are among the most massive and most luminous stars. Supergiant stars occupy the top region of the Hertzsprung–Russell diagram, with absolute visual magnitudes between about −3 and −8. The temperatures of supergiant stars range ...
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Blue supergiant
A blue supergiant (BSG) is a hot, luminous star, often referred to as an OB supergiant. They are usually considered to be those with luminosity class I and spectral class B9 or earlier, although sometimes A-class supergiants are also deemed blu ...
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Red supergiant
Red supergiants (RSGs) are stars with a supergiant luminosity class ( Yerkes class I) and a stellar classification K or M. They are the largest stars in the universe in terms of volume, although they are not the most massive or luminous. Betelg ...
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Yellow supergiant
A yellow supergiant (YSG) is a star, generally of spectral type F or G, having a supergiant luminosity class (e.g. Ia or Ib). They are stars that have evolved away from the main sequence, expanding and becoming more luminous.
Yellow supergiants ...
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Hypergiant
A hypergiant ( luminosity class 0 or Ia+) is a very rare type of star that has an extremely high luminosity, mass, size and mass loss because of its extreme stellar winds. The term ''hypergiant'' is defined as luminosity class 0 (zero) in the MK ...
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Yellow hypergiant
A yellow hypergiant (YHG) is a massive star with an extended atmosphere, a spectral class from A to K, and, starting with an initial mass of about 20–60 solar masses, has lost as much as half that mass. They are amongst the most visually lumino ...
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White dwarf
A white dwarf is a Compact star, stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very density, dense: in an Earth sized volume, it packs a mass that is comparable to the Sun. No nuclear fusion takes place i ...
* Remnants
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Supernova remnant
A supernova remnant (SNR) is the structure resulting from the explosion of a star in a supernova. The supernova remnant is bounded by an expanding shock wave, and consists of ejected material expanding from the explosion, and the interstellar mat ...
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Neutron star
A neutron star is the gravitationally collapsed Stellar core, core of a massive supergiant star. It results from the supernova explosion of a stellar evolution#Massive star, massive star—combined with gravitational collapse—that compresses ...
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Pulsar
A pulsar (''pulsating star, on the model of quasar'') is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its Poles of astronomical bodies#Magnetic poles, magnetic poles. This radiation can be obse ...
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Magnetar
A magnetar is a type of neutron star with an extremely powerful magnetic field (~109 to 1011 T, ~1013 to 1015 G). The magnetic-field decay powers the emission of high-energy electromagnetic radiation, particularly X-rays and gamma rays.Ward; Br ...
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Stellar black hole
A stellar black hole (or stellar-mass black hole) is a black hole formed by the gravitational collapse of a star. They have masses ranging from about 5 to several tens of solar masses. They are the remnants of supernova explosions, which may be ...
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Compact star
In astronomy, the term compact object (or compact star) refers collectively to white dwarfs, neutron stars, and black holes. It could also include exotic stars if such hypothetical, dense bodies are confirmed to exist. All compact objects have a ...
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Supergiant
Supergiants are among the most massive and most luminous stars. Supergiant stars occupy the top region of the Hertzsprung–Russell diagram, with absolute visual magnitudes between about −3 and −8. The temperatures of supergiant stars range ...
List of most massive stars
This is a list of the most massive stars that have been discovered, in solar mass units ().
Uncertainties and caveats
Most of the masses listed below are contested and, being the subject of current research, remain under review and subject to con ...
SN 1054
SN 1054, the Crab Supernova, is a supernova that was first observed on , and remained visible until .
The event was recorded in contemporary Chinese astronomy, and references to it are also found in a later (13th-century) Japanese document and ...
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Supergiant
Supergiants are among the most massive and most luminous stars. Supergiant stars occupy the top region of the Hertzsprung–Russell diagram, with absolute visual magnitudes between about −3 and −8. The temperatures of supergiant stars range ...
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Crab Nebula
The Crab Nebula (catalogue designations M1, NGC 1952, Taurus A) is a supernova remnant and pulsar wind nebula in the constellation of Taurus (constellation), Taurus. The common name comes from a drawing that somewhat resembled a crab with arm ...
SN 1987A
SN 1987A was a Type II supernova in the Large Magellanic Cloud, a dwarf satellite galaxy of the Milky Way. It occurred approximately from Earth and was the closest observed supernova since Kepler's Supernova in 1604. Light and neutrinos ...
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SN 185
SN 185 was a transient astronomical event observed in the year AD 185, likely a supernova
A supernova (: supernovae or supernovas) is a powerful and luminous explosion of a star. A supernova occurs during the last stellar evolution, evolut ...
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SN 1006
SN 1006 was a supernova that is likely the brightest observed stellar event in recorded history, reaching an estimated −7.5 visual magnitude, and exceeding roughly sixteen times the brightness of Venus. Appearing between April 30 and May 1, 1 ...
Nearby Supernova Factory
The Nearby Supernova Factory (SNfactory) is a collaborative experiment led by Greg Aldering, designed to collect data on more Type Ia supernovae than have ever been studied in a single project before, and by studying them, to increase understandin ...
Black hole
A black hole is a massive, compact astronomical object so dense that its gravity prevents anything from escaping, even light. Albert Einstein's theory of general relativity predicts that a sufficiently compact mass will form a black hole. Th ...
* Types
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Schwarzschild metric
In Einstein's theory of general relativity, the Schwarzschild metric (also known as the Schwarzschild solution) is an exact solution to the Einstein field equations that describes the gravitational field outside a spherical mass, on the assumpti ...
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Rotating black hole
A rotating black hole is a black hole that possesses angular momentum. In particular, it rotates about one of its axes of symmetry.
All currently known celestial objects, including planets, stars (Sun), galaxies, and black holes, spin about one ...
Stellar black hole
A stellar black hole (or stellar-mass black hole) is a black hole formed by the gravitational collapse of a star. They have masses ranging from about 5 to several tens of solar masses. They are the remnants of supernova explosions, which may be ...
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Intermediate-mass black hole
An intermediate-mass black hole (IMBH) is a class of black hole with mass in the range of one hundred to one hundred thousand (102–105) solar masses: significantly higher than stellar black holes but lower than the hundred thousand to more than ...
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Supermassive black hole
A supermassive black hole (SMBH or sometimes SBH) is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions, of times the mass of the Sun (). Black holes are a class of astronomical ...
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Quasar
A quasar ( ) is an extremely Luminosity, luminous active galactic nucleus (AGN). It is sometimes known as a quasi-stellar object, abbreviated QSO. The emission from an AGN is powered by accretion onto a supermassive black hole with a mass rangi ...
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Active galactic nucleus
An active galactic nucleus (AGN) is a compact region at the center of a galaxy that emits a significant amount of energy across the electromagnetic spectrum, with characteristics indicating that this luminosity is not produced by the stars. Such e ...
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Blazar
A blazar is an active galactic nucleus (AGN) with a relativistic jet (a jet composed of ionized matter traveling at nearly the speed of light) directed very nearly towards an observer. Relativistic beaming of electromagnetic radiation from the ...
* Formation
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Stellar evolution
Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is consi ...
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Gravitational collapse
Gravitational collapse is the contraction of an astronomical object due to the influence of its own gravity, which tends to draw matter inward toward the center of gravity. Gravitational collapse is a fundamental mechanism for structure formati ...
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Neutron star
A neutron star is the gravitationally collapsed Stellar core, core of a massive supergiant star. It results from the supernova explosion of a stellar evolution#Massive star, massive star—combined with gravitational collapse—that compresses ...
Compact star
In astronomy, the term compact object (or compact star) refers collectively to white dwarfs, neutron stars, and black holes. It could also include exotic stars if such hypothetical, dense bodies are confirmed to exist. All compact objects have a ...
Tolman–Oppenheimer–Volkoff limit
The Tolman–Oppenheimer–Volkoff limit (or TOV limit) is an upper bound to the mass of cold, non-rotating neutron stars, analogous to the Chandrasekhar limit for white dwarf stars. Stars more massive than the TOV limit collapse into a black hol ...
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White dwarf
A white dwarf is a Compact star, stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very density, dense: in an Earth sized volume, it packs a mass that is comparable to the Sun. No nuclear fusion takes place i ...
Supernova
A supernova (: supernovae or supernovas) is a powerful and luminous explosion of a star. A supernova occurs during the last stellar evolution, evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion ...
Hypernova
A hypernova is a very energetic supernova which is believed to result from an extreme core collapse scenario. In this case, a massive star (>30 solar masses) collapses to form a rotating black hole emitting twin astrophysical jets and surrounded b ...
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Gamma-ray burst
In gamma-ray astronomy, gamma-ray bursts (GRBs) are extremely energetic events occurring in distant Galaxy, galaxies which represent the brightest and most powerful class of explosion in the universe. These extreme Electromagnetic radiation, ele ...
* Properties
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Black hole thermodynamics
In physics, black hole thermodynamics is the area of study that seeks to reconcile the laws of thermodynamics with the existence of black hole event horizons. As the study of the statistical mechanics of black-body radiation led to the deve ...
M–sigma relation
The M–sigma (or ''M''–''σ'') relation is an empirical correlation between the stellar velocity dispersion ''σ'' of a galaxy bulge and the mass M of the supermassive black hole at its center.
The ''M''–''σ'' relation was first present ...
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Event horizon
In astrophysics, an event horizon is a boundary beyond which events cannot affect an outside observer. Wolfgang Rindler coined the term in the 1950s.
In 1784, John Michell proposed that gravity can be strong enough in the vicinity of massive c ...
Photon sphere
A photon sphere, or photon ring or photon circle, arises in a neighbourhood of the event horizon of a black hole where gravity is so strong that emitted photons will not just bend around the black hole but also return to the point where they we ...
Hawking radiation
Hawking radiation is black-body radiation released outside a black hole's event horizon due to quantum effects according to a model developed by Stephen Hawking in 1974.
The radiation was not predicted by previous models which assumed that onc ...
Spaghettification
In astrophysics, spaghettification (sometimes referred to as the noodle effect) is the vertical stretching and horizontal compression of objects into long thin shapes (rather like spaghetti) in a very strong, non- homogeneous gravitational fi ...
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Gravitational lens
A gravitational lens is matter, such as a galaxy cluster, cluster of galaxies or a point particle, that bends light from a distant source as it travels toward an observer. The amount of gravitational lensing is described by Albert Einstein's Ge ...
* Models
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Gravitational singularity
A gravitational singularity, spacetime singularity, or simply singularity, is a theoretical condition in which gravity is predicted to be so intense that spacetime itself would break down catastrophically. As such, a singularity is by defini ...
White hole
In general relativity, a white hole is a hypothetical region of spacetime and Gravitational singularity, singularity that cannot be entered from the outside, although energy, matter, light and information can escape from it. In this sense, it is ...
Wormhole
A wormhole is a hypothetical structure that connects disparate points in spacetime. It can be visualized as a tunnel with two ends at separate points in spacetime (i.e., different locations, different points in time, or both). Wormholes are base ...
No-hair theorem
The no-hair theorem states that all stationary black hole solutions of the Einstein–Maxwell equations of gravitation and electromagnetism in general relativity can be completely characterized by only three independent ''externally'' observabl ...
Cosmic censorship hypothesis
The weak and the strong cosmic censorship hypotheses are two mathematical conjectures about the structure of gravitational singularities arising in general relativity.
Singularities that arise in the solutions of Einstein's equations are typical ...
Black hole complementarity
Black hole complementarity is a conjectured solution to the black hole information paradox, proposed by Leonard Susskind, Lárus Thorlacius, John Uglum, and Gerard 't Hooft.
Overview
Ever since Stephen Hawking suggested information is lost in an ...
* Metrics
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Schwarzschild metric
In Einstein's theory of general relativity, the Schwarzschild metric (also known as the Schwarzschild solution) is an exact solution to the Einstein field equations that describes the gravitational field outside a spherical mass, on the assumpti ...
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Kerr metric
The Kerr metric or Kerr geometry describes the geometry of empty spacetime around a rotating uncharged axially symmetric black hole with a quasispherical event horizon. The Kerr metric is an exact solution of the Einstein field equations of gen ...
List of black holes
This list of black holes (and stars considered probable candidates) is organized by mass (including black holes of undetermined mass); some items in this list are Galaxy, galaxies or star clusters that are believed to be organized around a black ...
Constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object.
The first constellati ...
Antlia
Antlia (; from Ancient Greek ''ἀντλία'') is a constellation in the Southern Celestial Hemisphere. Its name means "pump" in Latin and Greek language, Greek; it represents an air pump. Originally Antlia Pneumatica, the constellation was es ...
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Apus
Apus is a small constellation in the Southern Celestial Hemisphere, southern sky. It represents a bird-of-paradise, and its name means "without feet" in Greek language, Greek because the bird-of-paradise was once wrongly believed to lack feet. ...
Boötes
Boötes ( ) is a constellation in the northern sky, located between 0° and +60° declination, and 13 and 16 hours of right ascension on the celestial sphere. The name comes from , which comes from 'herder, herdsman' or 'plowman' (literally, 'o ...
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Caelum
Caelum is a faint constellation in the southern sky, introduced in the 1750s by Nicolas Louis de Lacaille and counted among the 88 modern constellations. Its name means "chisel" in Latin, and it was formerly known as Caelum Sculptorium ("Engrave ...
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Camelopardalis
Camelopardalis is a large but faint constellation of the northern sky representing a giraffe. The constellation was introduced in 1612 or 1613 by Petrus Plancius. Some older astronomy books give Camelopardalus or Camelopardus as alternative form ...
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Cancer
Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Po ...
*
Canes Venatici
Canes Venatici ( ) is one of the 88 constellations designated by the International Astronomical Union (IAU). It is a small northern constellation that was created by Johannes Hevelius in the 17th century. Its name is Latin for 'hunting dogs', and ...
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Canis Major
Canis Major is a constellation in the southern celestial hemisphere. In the second century, it was included in Ptolemy's 48 constellations, and is counted among the 88 modern constellations. Its name is Latin for "greater dog" in contrast to C ...
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Canis Minor
Canis Minor is a small constellation in the Celestial sphere, northern celestial hemisphere. In the second century, it was included as an Asterism (astronomy), asterism, or pattern, of two stars in Ptolemy's 48 constellations, and it is counte ...
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Capricornus
Capricornus is one of the constellations of the zodiac. Its name is Latin for "horned goat" or "goat Horn (anatomy), horn" or "having horns like a goat's", and it is commonly represented in the form of a sea goat: a mythical creature that is hal ...
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Carina
Carina may refer to:
Places
Australia
* Carina, Queensland, a suburb in Brisbane
* Carina Heights, Queensland, a suburb in Brisbane
* Carina, Victoria, a locality in Mildura
Serbia
* Carina, Osečina, a village in the Kolubara District
...
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Cassiopeia
Cassiopeia or Cassiopea may refer to:
Greek mythology
* Cassiopeia (mother of Andromeda), queen of Aethiopia and mother of Andromeda
* Cassiopeia (wife of Phoenix), wife of Phoenix, king of Phoenicia
* Cassiopeia, wife of Epaphus, king of Egy ...
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Centaurus
Centaurus () is a bright constellation in the southern sky. One of the 88 modern constellations by area, largest constellations, Centaurus was included among the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one ...
Cetus
Cetus () is a constellation, sometimes called 'the whale' in English. The Cetus (mythology), Cetus was a sea monster in Greek mythology which both Perseus and Heracles needed to slay. Cetus is in the region of the sky that contains other water- ...
Columba
Columba () or Colmcille (7 December 521 – 9 June 597 AD) was an Irish abbot and missionary evangelist credited with spreading Christianity in what is today Scotland at the start of the Hiberno-Scottish mission. He founded the important abbey ...
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Coma Berenices
Coma Berenices is an ancient asterism in the northern sky, which has been defined as one of the 88 modern constellations. It is in the direction of the fourth galactic quadrant, between Leo and Boötes, and it is visible in both hemispher ...
Corona Borealis
Corona Borealis is a small constellation in the Northern Celestial Hemisphere. It is one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and remains one of the 88 modern constellations. Its brightest stars form a sem ...
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Corvus
''Corvus'' is a widely distributed genus of passerine birds ranging from medium-sized to large-sized in the family Corvidae. It includes species commonly known as crows, ravens, and rooks. The species commonly encountered in Europe are the car ...
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Crater
A crater is a landform consisting of a hole or depression (geology), depression on a planetary surface, usually caused either by an object hitting the surface, or by geological activity on the planet. A crater has classically been described ...
*
Crux
CRUX is a lightweight x86-64 Linux distribution targeted at experienced Linux users and delivered by a tar.gz-based package system with BSD-style initscripts. It is not based on any other Linux distribution. It also utilizes a ports system ...
Dorado
Dorado (, ) is a constellation in the Southern Sky. It was named in the late 16th century and is now one of the 88 modern constellations. Its name refers to the mahi-mahi (''Coryphaena hippurus''), which is known as ''dorado'' ("golden") in Sp ...
Equuleus
Equuleus is a faint constellation located just north of the celestial equator. Its name is Latin for "little horse", a foal. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains one of the 88 modern const ...
Fornax
Fornax () is a constellation in the southern celestial hemisphere, partly ringed by the celestial river Eridanus (constellation), Eridanus. Its name is Latin for furnace. It was named by French astronomer Nicolas Louis de Lacaille in 1756. Forna ...
Hercules
Hercules (, ) is the Roman equivalent of the Greek divine hero Heracles, son of Jupiter and the mortal Alcmena. In classical mythology, Hercules is famous for his strength and for his numerous far-ranging adventures.
The Romans adapted the Gr ...
Hydrus
Hydrus is a small constellation in the deep Southern Celestial Hemisphere, southern sky. It was one of twelve constellations created by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman and it first ap ...
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Indus
The Indus ( ) is a transboundary river of Asia and a trans- Himalayan river of South and Central Asia. The river rises in mountain springs northeast of Mount Kailash in the Western Tibet region of China, flows northwest through the dis ...
Leo Minor
Leo Minor is a small and faint constellation in the northern celestial hemisphere. Its name is Latin for "the smaller lion", in contrast to Leo, the larger lion. It lies between the larger and more recognizable Ursa Major to the north and Leo ...
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Lepus
Hares and jackrabbits are mammals belonging to the genus ''Lepus''. They are herbivores and live solitarily or in pairs. They nest in slight depressions called forms, and their young are able to fend for themselves shortly after birth. The genu ...
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Libra
Libra generally refers to:
* Libra (constellation), a constellation
* Libra (astrology), an astrological sign based on the star constellation
Libra may also refer to:
Arts and entertainment
* ''Libra'' (novel), a 1988 novel by Don DeLillo
Musi ...
*
Lupus
Lupus, formally called systemic lupus erythematosus (SLE), is an autoimmune disease in which the body's immune system mistakenly attacks healthy tissue in many parts of the body. Symptoms vary among people and may be mild to severe. Common ...
*
Lynx
A lynx ( ; : lynx or lynxes) is any of the four wikt:extant, extant species (the Canada lynx, Iberian lynx, Eurasian lynx and the bobcat) within the medium-sized wild Felidae, cat genus ''Lynx''. The name originated in Middle Engl ...
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Lyra
, from ; pronounced: ) is a small constellation. It is one of the 48 listed by the 2nd century astronomer Ptolemy, and is one of the modern 88 constellations recognized by the International Astronomical Union. Lyra was often represented on star ...
Microscopium
Microscopium ("the Microscope") is a minor constellation in the southern celestial hemisphere, one of twelve created in the 18th century by French astronomer Nicolas-Louis de Lacaille and one of several depicting scientific instruments. The name ...
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Monoceros
Monoceros ( Greek: , "unicorn") is a faint constellation on the celestial equator. Its definition is attributed to the 17th-century cartographer Petrus Plancius. It is bordered by Orion to the west, Gemini to the north, Canis Major to the s ...
Norma Norma may refer to:
* Norma (given name), a given name (including a list of people with the name)
** Norma Lizbeth Ramos, a Mexican bullying victim
Astronomy
*Norma (constellation)
* 555 Norma, a minor asteroid
* Cygnus Arm or Norma Arm, a spiral ...
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Octans
Octans is a faint constellation located in the deep southern celestial hemisphere, Southern Sky. Its name is Latin for the eighth part of a circle, but it is named after the octant (instrument), octant, a navigational instrument. Devised by kingd ...
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Ophiuchus
Ophiuchus () is a large constellation straddling the celestial equator. Its name comes from the Ancient Greek (), meaning "serpent-bearer", and it is commonly represented as a man grasping a snake. The serpent is represented by the constellati ...
Pegasus
Pegasus (; ) is a winged horse in Greek mythology, usually depicted as a white stallion. He was sired by Poseidon, in his role as horse-god, and foaled by the Gorgon Medusa. Pegasus was the brother of Chrysaor, both born from Medusa's blood w ...
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Perseus
In Greek mythology, Perseus (, ; Greek language, Greek: Περσεύς, Romanization of Greek, translit. Perseús) is the legendary founder of the Perseid dynasty. He was, alongside Cadmus and Bellerophon, the greatest Greek hero and slayer of ...
Piscis Austrinus
Piscis Austrinus is a constellation in the southern celestial hemisphere. The name is Latin for "the southern fish", in contrast with the larger constellation Pisces, which represents a pair of fish. Before the 20th century, it was also known as ...
*
Puppis
Puppis ("poop deck, stern") is a constellation in the southern sky. It was originally part of the Former constellations, traditional constellation of Argo Navis (the ship of Jason and the Argonauts), which was divided into three parts, the other ...
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Pyxis
Pyxis is a small and faint constellation in the southern sky. Abbreviated from Pyxis Nautica, its name is Latin for a mariner's compass (contrasting with Circinus, which represents a draftsman's compasses). Pyxis was introduced by Nicolas-Louis ...
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Reticulum
Reticulum is a small, faint constellation in the southern sky. Its name is Latin for a small net, or reticle—a net of crosshairs at the focus of a telescope eyepiece that is used to measure star positions. The constellation is best viewed b ...
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Sagitta
Sagitta is a dim but distinctive constellation in the northern sky. Its name is Latin for 'arrow', not to be confused with the significantly larger constellation Sagittarius 'the archer'. It was included among the 48 constellations listed by t ...
Scorpius
Scorpius is a zodiac constellation located in the Southern celestial hemisphere, where it sits near the center of the Milky Way, between Libra to the west and Sagittarius to the east. Scorpius is an ancient constellation whose recognition pred ...
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Sculptor
Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable sc ...
Serpens
Serpens () is a constellation in the northern celestial hemisphere. One of the 48 constellations listed by the 2nd-century astronomer Ptolemy, it remains one of the 88 modern constellations designated by the International Astronomical Union. It ...
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Sextans
Sextans is a faint, minor constellation on the celestial equator which was introduced in 1687 by Polish astronomer Johannes Hevelius. Its name is Latin for the astronomical sextant, an instrument that Hevelius made frequent use of in his obs ...
Telescopium
Telescopium is a minor constellation in the southern Celestial sphere, celestial hemisphere, one of twelve named in the 18th century by French astronomer Nicolas-Louis de Lacaille and one of several depicting scientific instruments. Its name i ...
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Triangulum
Triangulum is a small constellation in the northern sky. Its name is Latin for "triangle", derived from its three brightest stars, which form a long and narrow triangle. Known to the ancient Babylonians and Greeks, Triangulum was one of the 48 ...
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Triangulum Australe
Triangulum Australe is a small constellation in the far Southern Celestial Hemisphere. Its name is Latin for "the southern triangle", which distinguishes it from Triangulum in the northern sky and is derived from the Acute triangle, acute, almost ...
Ursa Major
Ursa Major, also known as the Great Bear, is a constellation in the Northern Sky, whose associated mythology likely dates back into prehistory. Its Latin name means "greater (or larger) bear", referring to and contrasting it with nearby Ursa M ...
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Ursa Minor
Ursa Minor (, contrasting with Ursa Major), also known as the Little Bear, is a constellation located in the far northern celestial hemisphere, northern sky. As with the Great Bear, the tail of the Little Bear may also be seen as the handle of ...
Virgo
Virgo may refer to:
Arts and entertainment
* Virgo (film), a 1970 Egyptian film
* Virgo (character), several Marvel Comics characters
* Virgo Asmita, a character in the manga ''Saint Seiya: The Lost Canvas''
* ''Virgo'' (album), by Virgo Four, ...
Vulpecula
Vulpecula is a faint constellation in the northern sky. Its name is Latin for "little fox", although it is commonly known simply as the fox. It was identified in the seventeenth century, and is located in the middle of the Summer Triangle (an ...
Constellation history
= The 48 constellations listed by
Ptolemy
Claudius Ptolemy (; , ; ; – 160s/170s AD) was a Greco-Roman mathematician, astronomer, astrologer, geographer, and music theorist who wrote about a dozen scientific treatises, three of which were important to later Byzantine science, Byzant ...
Argo Navis
Argo Navis (the Ship Argo), or simply Argo, is one of Ptolemy's 48 constellations, now a grouping of three IAU constellations. It is formerly a single large constellation in the southern sky. The genitive is "Argus Navis", abbreviated "Arg". ...
Boötes
Boötes ( ) is a constellation in the northern sky, located between 0° and +60° declination, and 13 and 16 hours of right ascension on the celestial sphere. The name comes from , which comes from 'herder, herdsman' or 'plowman' (literally, 'o ...
*
Cancer
Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Po ...
*
Canis Major
Canis Major is a constellation in the southern celestial hemisphere. In the second century, it was included in Ptolemy's 48 constellations, and is counted among the 88 modern constellations. Its name is Latin for "greater dog" in contrast to C ...
*
Canis Minor
Canis Minor is a small constellation in the Celestial sphere, northern celestial hemisphere. In the second century, it was included as an Asterism (astronomy), asterism, or pattern, of two stars in Ptolemy's 48 constellations, and it is counte ...
*
Capricornus
Capricornus is one of the constellations of the zodiac. Its name is Latin for "horned goat" or "goat Horn (anatomy), horn" or "having horns like a goat's", and it is commonly represented in the form of a sea goat: a mythical creature that is hal ...
*
Cassiopeia
Cassiopeia or Cassiopea may refer to:
Greek mythology
* Cassiopeia (mother of Andromeda), queen of Aethiopia and mother of Andromeda
* Cassiopeia (wife of Phoenix), wife of Phoenix, king of Phoenicia
* Cassiopeia, wife of Epaphus, king of Egy ...
*
Centaurus
Centaurus () is a bright constellation in the southern sky. One of the 88 modern constellations by area, largest constellations, Centaurus was included among the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one ...
Cetus
Cetus () is a constellation, sometimes called 'the whale' in English. The Cetus (mythology), Cetus was a sea monster in Greek mythology which both Perseus and Heracles needed to slay. Cetus is in the region of the sky that contains other water- ...
Corona Borealis
Corona Borealis is a small constellation in the Northern Celestial Hemisphere. It is one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and remains one of the 88 modern constellations. Its brightest stars form a sem ...
*
Corvus
''Corvus'' is a widely distributed genus of passerine birds ranging from medium-sized to large-sized in the family Corvidae. It includes species commonly known as crows, ravens, and rooks. The species commonly encountered in Europe are the car ...
*
Crater
A crater is a landform consisting of a hole or depression (geology), depression on a planetary surface, usually caused either by an object hitting the surface, or by geological activity on the planet. A crater has classically been described ...
Equuleus
Equuleus is a faint constellation located just north of the celestial equator. Its name is Latin for "little horse", a foal. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains one of the 88 modern const ...
Hercules
Hercules (, ) is the Roman equivalent of the Greek divine hero Heracles, son of Jupiter and the mortal Alcmena. In classical mythology, Hercules is famous for his strength and for his numerous far-ranging adventures.
The Romans adapted the Gr ...
Lepus
Hares and jackrabbits are mammals belonging to the genus ''Lepus''. They are herbivores and live solitarily or in pairs. They nest in slight depressions called forms, and their young are able to fend for themselves shortly after birth. The genu ...
*
Libra
Libra generally refers to:
* Libra (constellation), a constellation
* Libra (astrology), an astrological sign based on the star constellation
Libra may also refer to:
Arts and entertainment
* ''Libra'' (novel), a 1988 novel by Don DeLillo
Musi ...
*
Lupus
Lupus, formally called systemic lupus erythematosus (SLE), is an autoimmune disease in which the body's immune system mistakenly attacks healthy tissue in many parts of the body. Symptoms vary among people and may be mild to severe. Common ...
*
Lyra
, from ; pronounced: ) is a small constellation. It is one of the 48 listed by the 2nd century astronomer Ptolemy, and is one of the modern 88 constellations recognized by the International Astronomical Union. Lyra was often represented on star ...
*
Ophiuchus
Ophiuchus () is a large constellation straddling the celestial equator. Its name comes from the Ancient Greek (), meaning "serpent-bearer", and it is commonly represented as a man grasping a snake. The serpent is represented by the constellati ...
Pegasus
Pegasus (; ) is a winged horse in Greek mythology, usually depicted as a white stallion. He was sired by Poseidon, in his role as horse-god, and foaled by the Gorgon Medusa. Pegasus was the brother of Chrysaor, both born from Medusa's blood w ...
*
Perseus
In Greek mythology, Perseus (, ; Greek language, Greek: Περσεύς, Romanization of Greek, translit. Perseús) is the legendary founder of the Perseid dynasty. He was, alongside Cadmus and Bellerophon, the greatest Greek hero and slayer of ...
Piscis Austrinus
Piscis Austrinus is a constellation in the southern celestial hemisphere. The name is Latin for "the southern fish", in contrast with the larger constellation Pisces, which represents a pair of fish. Before the 20th century, it was also known as ...
*
Sagitta
Sagitta is a dim but distinctive constellation in the northern sky. Its name is Latin for 'arrow', not to be confused with the significantly larger constellation Sagittarius 'the archer'. It was included among the 48 constellations listed by t ...
Scorpius
Scorpius is a zodiac constellation located in the Southern celestial hemisphere, where it sits near the center of the Milky Way, between Libra to the west and Sagittarius to the east. Scorpius is an ancient constellation whose recognition pred ...
*
Serpens
Serpens () is a constellation in the northern celestial hemisphere. One of the 48 constellations listed by the 2nd-century astronomer Ptolemy, it remains one of the 88 modern constellations designated by the International Astronomical Union. It ...
Triangulum
Triangulum is a small constellation in the northern sky. Its name is Latin for "triangle", derived from its three brightest stars, which form a long and narrow triangle. Known to the ancient Babylonians and Greeks, Triangulum was one of the 48 ...
*
Ursa Major
Ursa Major, also known as the Great Bear, is a constellation in the Northern Sky, whose associated mythology likely dates back into prehistory. Its Latin name means "greater (or larger) bear", referring to and contrasting it with nearby Ursa M ...
*
Ursa Minor
Ursa Minor (, contrasting with Ursa Major), also known as the Little Bear, is a constellation located in the far northern celestial hemisphere, northern sky. As with the Great Bear, the tail of the Little Bear may also be seen as the handle of ...
*
Virgo
Virgo may refer to:
Arts and entertainment
* Virgo (film), a 1970 Egyptian film
* Virgo (character), several Marvel Comics characters
* Virgo Asmita, a character in the manga ''Saint Seiya: The Lost Canvas''
* ''Virgo'' (album), by Virgo Four, ...
= The 41 additional constellations added in the 16th and 17th centuries
=
* ''Vespucci or Corsalius early 16c'':
Crux
CRUX is a lightweight x86-64 Linux distribution targeted at experienced Linux users and delivered by a tar.gz-based package system with BSD-style initscripts. It is not based on any other Linux distribution. It also utilizes a ports system ...
*
Triangulum Australe
Triangulum Australe is a small constellation in the far Southern Celestial Hemisphere. Its name is Latin for "the southern triangle", which distinguishes it from Triangulum in the northern sky and is derived from the Acute triangle, acute, almost ...
▶ ''Vopel'' 1536:
Coma Berenices
Coma Berenices is an ancient asterism in the northern sky, which has been defined as one of the 88 modern constellations. It is in the direction of the fourth galactic quadrant, between Leo and Boötes, and it is visible in both hemispher ...
▶ ''Keyser & de Houtman'' 1596:
Apus
Apus is a small constellation in the Southern Celestial Hemisphere, southern sky. It represents a bird-of-paradise, and its name means "without feet" in Greek language, Greek because the bird-of-paradise was once wrongly believed to lack feet. ...
Dorado
Dorado (, ) is a constellation in the Southern Sky. It was named in the late 16th century and is now one of the 88 modern constellations. Its name refers to the mahi-mahi (''Coryphaena hippurus''), which is known as ''dorado'' ("golden") in Sp ...
Hydrus
Hydrus is a small constellation in the deep Southern Celestial Hemisphere, southern sky. It was one of twelve constellations created by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman and it first ap ...
*
Indus
The Indus ( ) is a transboundary river of Asia and a trans- Himalayan river of South and Central Asia. The river rises in mountain springs northeast of Mount Kailash in the Western Tibet region of China, flows northwest through the dis ...
Camelopardalis
Camelopardalis is a large but faint constellation of the northern sky representing a giraffe. The constellation was introduced in 1612 or 1613 by Petrus Plancius. Some older astronomy books give Camelopardalus or Camelopardus as alternative form ...
*
Columba
Columba () or Colmcille (7 December 521 – 9 June 597 AD) was an Irish abbot and missionary evangelist credited with spreading Christianity in what is today Scotland at the start of the Hiberno-Scottish mission. He founded the important abbey ...
*
Monoceros
Monoceros ( Greek: , "unicorn") is a faint constellation on the celestial equator. Its definition is attributed to the 17th-century cartographer Petrus Plancius. It is bordered by Orion to the west, Gemini to the north, Canis Major to the s ...
▶ ''Habrecht'' 1621:
Reticulum
Reticulum is a small, faint constellation in the southern sky. Its name is Latin for a small net, or reticle—a net of crosshairs at the focus of a telescope eyepiece that is used to measure star positions. The constellation is best viewed b ...
▶ ''Hevelius'' 1683:
Canes Venatici
Canes Venatici ( ) is one of the 88 constellations designated by the International Astronomical Union (IAU). It is a small northern constellation that was created by Johannes Hevelius in the 17th century. Its name is Latin for 'hunting dogs', and ...
Leo Minor
Leo Minor is a small and faint constellation in the northern celestial hemisphere. Its name is Latin for "the smaller lion", in contrast to Leo, the larger lion. It lies between the larger and more recognizable Ursa Major to the north and Leo ...
*
Lynx
A lynx ( ; : lynx or lynxes) is any of the four wikt:extant, extant species (the Canada lynx, Iberian lynx, Eurasian lynx and the bobcat) within the medium-sized wild Felidae, cat genus ''Lynx''. The name originated in Middle Engl ...
Sextans
Sextans is a faint, minor constellation on the celestial equator which was introduced in 1687 by Polish astronomer Johannes Hevelius. Its name is Latin for the astronomical sextant, an instrument that Hevelius made frequent use of in his obs ...
*
Vulpecula
Vulpecula is a faint constellation in the northern sky. Its name is Latin for "little fox", although it is commonly known simply as the fox. It was identified in the seventeenth century, and is located in the middle of the Summer Triangle (an ...
▶ ''de Lacaille'' 1763:
Antlia
Antlia (; from Ancient Greek ''ἀντλία'') is a constellation in the Southern Celestial Hemisphere. Its name means "pump" in Latin and Greek language, Greek; it represents an air pump. Originally Antlia Pneumatica, the constellation was es ...
*
Caelum
Caelum is a faint constellation in the southern sky, introduced in the 1750s by Nicolas Louis de Lacaille and counted among the 88 modern constellations. Its name means "chisel" in Latin, and it was formerly known as Caelum Sculptorium ("Engrave ...
*
Carina
Carina may refer to:
Places
Australia
* Carina, Queensland, a suburb in Brisbane
* Carina Heights, Queensland, a suburb in Brisbane
* Carina, Victoria, a locality in Mildura
Serbia
* Carina, Osečina, a village in the Kolubara District
...
Fornax
Fornax () is a constellation in the southern celestial hemisphere, partly ringed by the celestial river Eridanus (constellation), Eridanus. Its name is Latin for furnace. It was named by French astronomer Nicolas Louis de Lacaille in 1756. Forna ...
Microscopium
Microscopium ("the Microscope") is a minor constellation in the southern celestial hemisphere, one of twelve created in the 18th century by French astronomer Nicolas-Louis de Lacaille and one of several depicting scientific instruments. The name ...
*
Norma Norma may refer to:
* Norma (given name), a given name (including a list of people with the name)
** Norma Lizbeth Ramos, a Mexican bullying victim
Astronomy
*Norma (constellation)
* 555 Norma, a minor asteroid
* Cygnus Arm or Norma Arm, a spiral ...
*
Octans
Octans is a faint constellation located in the deep southern celestial hemisphere, Southern Sky. Its name is Latin for the eighth part of a circle, but it is named after the octant (instrument), octant, a navigational instrument. Devised by kingd ...
Puppis
Puppis ("poop deck, stern") is a constellation in the southern sky. It was originally part of the Former constellations, traditional constellation of Argo Navis (the ship of Jason and the Argonauts), which was divided into three parts, the other ...
*
Pyxis
Pyxis is a small and faint constellation in the southern sky. Abbreviated from Pyxis Nautica, its name is Latin for a mariner's compass (contrasting with Circinus, which represents a draftsman's compasses). Pyxis was introduced by Nicolas-Louis ...
*
Sculptor
Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable sc ...
*
Telescopium
Telescopium is a minor constellation in the southern Celestial sphere, celestial hemisphere, one of twelve named in the 18th century by French astronomer Nicolas-Louis de Lacaille and one of several depicting scientific instruments. Its name i ...
Antinous
Antinous, also called Antinoös, (; ; – ) was a Greek youth from Bithynia, a favourite and lover of the Roman emperor Hadrian. Following his premature death before his 20th birthday, Antinous was deified on Hadrian's orders, being worshippe ...
*
Argo Navis
Argo Navis (the Ship Argo), or simply Argo, is one of Ptolemy's 48 constellations, now a grouping of three IAU constellations. It is formerly a single large constellation in the southern sky. The genitive is "Argus Navis", abbreviated "Arg". ...
*
Asterion
In Greek mythology, Asterion (Ancient Greek, Greek: , gen.: , literally "starry") or Asterius () may refer to the following figures:
* Asterion (god), Asterion, one of the River gods (Greek mythology), river gods.
* Asterius (giant), Asterius ...
Cerberus
In Greek mythology, Cerberus ( or ; ''Kérberos'' ), often referred to as the hound of Hades, is a polycephaly, multi-headed dog that guards the gates of the Greek underworld, underworld to prevent the dead from leaving. He was the offspring o ...
Felis
''Felis'' is a genus of small and medium-sized cat species native to most of Africa and south of 60° latitude in Europe and Asia to Indochina. The genus includes the domestic cat. The smallest of the seven ''Felis'' species is the black-footed ...
Malus
''Malus'' ( or ) is a genus of about 32–57 species of small deciduous trees or shrubs in the family Rosaceae, including the domesticated orchard apple, crab apples (sometimes known in North America as crabapples) and wild apples.
The genus i ...
Solarium
Solarium may refer to:
* A sunroom, a room built largely of glass to afford exposure to the sun
* A terrace (building) or flat housetop
* The '' Solarium Augusti'', a monumental meridian line (or perhaps a sundial) erected in Rome by Emperor Aug ...
Taurus Poniatovii
Taurus Poniatovii (Latin for ''Poniatowski's bull'') was a constellation created by the former rector of Vilnius University, Marcin Odlanicki Poczobutt, in 1777 to honor Stanislaus II Augustus Poniatowski of Poland, Stanislaus Poniatowski, King of ...
Tigris
The Tigris ( ; see #Etymology, below) is the eastern of the two great rivers that define Mesopotamia, the other being the Euphrates. The river flows south from the mountains of the Armenian Highlands through the Syrian Desert, Syrian and Arabia ...
Vespa
Vespa () is an Italian brand of scooters and mopeds manufactured by Piaggio. The name means wasp in Italian. The Vespa has evolved from a single model motor scooter manufactured in 1946 by Piaggio & Co. S.p.A. of Pontedera, Italy, to a ...
Nebula
A nebula (; or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral, or molecular hydrogen and also cosmic dust. Nebulae are often star-forming regions, such as in the Pillars of Creation in ...
*
Crab Nebula
The Crab Nebula (catalogue designations M1, NGC 1952, Taurus A) is a supernova remnant and pulsar wind nebula in the constellation of Taurus (constellation), Taurus. The common name comes from a drawing that somewhat resembled a crab with arm ...
*
H I region
An HI region or H I region (read ''H one'') is a cloud in the interstellar medium composed of neutral atomic hydrogen (HI), in addition to the local abundance of helium and other elements. (H is the chemical symbol for hydrogen, and "I" is the Ro ...
*
H II region
An H II region is a region of interstellar atomic hydrogen that is ionized. It is typically in a molecular cloud of partially ionized gas in which star formation has recently taken place, with a size ranging from one to hundreds of light year ...
*
Orion nebula
The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a diffuse nebula in the Milky Way situated south of Orion's Belt in the Orion (constellation), constellation of Orion, and is known as the middle "star" in the "sword" of Orion. It ...
*
Planetary nebula
A planetary nebula is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives.
The term "planetary nebula" is a misnomer because they are unrelated to planets. The ...
*
Pleiades
The Pleiades (), also known as Seven Sisters and Messier 45 (M45), is an Asterism (astronomy), asterism of an open cluster, open star cluster containing young Stellar classification#Class B, B-type stars in the northwest of the constellation Tau ...
Galaxies
*
Galaxy
A galaxy is a Physical system, system of stars, stellar remnants, interstellar medium, interstellar gas, cosmic dust, dust, and dark matter bound together by gravity. The word is derived from the Ancient Greek, Greek ' (), literally 'milky', ...
*
Andromeda Galaxy
The Andromeda Galaxy is a barred spiral galaxy and is the nearest major galaxy to the Milky Way. It was originally named the Andromeda Nebula and is cataloged as Messier 31, M31, and NGC 224. Andromeda has a Galaxy#Isophotal diameter, D25 isop ...
*
Magellanic Clouds
The Magellanic Clouds (''Magellanic system'' or ''Nubeculae Magellani'') are two irregular dwarf galaxies in the southern celestial hemisphere. Orbiting the Milky Way galaxy, these satellite galaxies are members of the Local Group. Because both ...
*
Quasar
A quasar ( ) is an extremely Luminosity, luminous active galactic nucleus (AGN). It is sometimes known as a quasi-stellar object, abbreviated QSO. The emission from an AGN is powered by accretion onto a supermassive black hole with a mass rangi ...
Cosmology
*
Big Bang
The Big Bang is a physical theory that describes how the universe expanded from an initial state of high density and temperature. Various cosmological models based on the Big Bang concept explain a broad range of phenomena, including th ...
*
Cosmic microwave background
The cosmic microwave background (CMB, CMBR), or relic radiation, is microwave radiation that fills all space in the observable universe. With a standard optical telescope, the background space between stars and galaxies is almost completely dar ...
*
Cosmos
The cosmos (, ; ) is an alternative name for the universe or its nature or order. Usage of the word ''cosmos'' implies viewing the universe as a complex and orderly system or entity.
The cosmos is studied in cosmologya broad discipline covering ...
*
Dark matter
In astronomy, dark matter is an invisible and hypothetical form of matter that does not interact with light or other electromagnetic radiation. Dark matter is implied by gravity, gravitational effects that cannot be explained by general relat ...
*
Cosmic distance ladder
The cosmic distance ladder (also known as the extragalactic distance scale) is the succession of methods by which astronomers determine the distances to celestial objects. A ''direct'' distance measurement of an astronomical object is possible ...
*
Hubble constant
Hubble's law, also known as the Hubble–Lemaître law, is the observation in physical cosmology that galaxies are moving away from Earth at speeds proportional to their distance. In other words, the farther a galaxy is from the Earth, the faste ...
Universe
The universe is all of space and time and their contents. It comprises all of existence, any fundamental interaction, physical process and physical constant, and therefore all forms of matter and energy, and the structures they form, from s ...
Canadian Space Agency
The Canadian Space Agency (CSA; ) is the national space agency of Canada, established in 1990 by the ''Canadian Space Agency Act''.
The President of the Canadian Space Agency, president is Lisa Campbell (civil servant), Lisa Campbell, who took ...
*
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...
*
United States Department of Defense
The United States Department of Defense (DoD, USDOD, or DOD) is an United States federal executive departments, executive department of the federal government of the United States, U.S. federal government charged with coordinating and superv ...
**
National Reconnaissance Office
The National Reconnaissance Office (NRO) is a member of the United States Intelligence Community and an agency of the United States Department of Defense which designs, builds, launches, and operates the reconnaissance satellites of the U.S. f ...
United States Space Command
United States Space Command (USSPACECOM or SPACECOM) is a unified combatant command of the United States Department of Defense, responsible for military operations in outer space, specifically all operations 100 kilometers (62 miles) and greater ...
**
United States Space Force
The United States Space Force (USSF) is the space force branch of the United States Department of Defense. It is one of the six United States Armed Forces, armed forces of the United States and one of the eight uniformed services of the Unite ...
Brazilian Space Agency
The Brazilian Space Agency (; AEB) is the civilian authority in Brazil responsible for the country's Space exploration, space program. It operates a spaceport at Centro de Lançamento de Alcântara, Alcântara, and a rocket launch site at Centro ...
*
Brazilian General Command for Aerospace Technology
The Brazilian Department of Science and Aerospace Technology (; DCTA) is the national military research center for aviation and space flight. It is subordinated to the Brazilian Air Force (FAB).
It coordinates all technical and scientific activiti ...
Comisión Nacional de Actividades Espaciales
The National Space Activities Commission ( Spanish: ''Comisión Nacional de Actividades Espaciales'', CONAE) is the civilian agency of the government of Argentina in charge of the national space programme.
History Sociedad Argentina Interp ...
National Institute for Space Research
The National Institute for Space Research (, INPE) is a research unit of the Brazilian Ministry of Science, Technology and Innovation (Brazil), Ministry of Science, Technology and Innovations, the main goals of which are fostering scientific r ...
=Asia
=
East Asia
*
China Aerospace Science and Technology Corporation
The China Aerospace Science and Technology Corporation (CASC) is a main contractor for the Chinese space program. It is state-owned and has subsidiaries which design, develop and manufacture a range of spacecraft, launch vehicles, and ground equ ...
China Aerospace Science and Technology Corporation
The China Aerospace Science and Technology Corporation (CASC) is a main contractor for the Chinese space program. It is state-owned and has subsidiaries which design, develop and manufacture a range of spacecraft, launch vehicles, and ground equ ...
* Commission for Science, Technology and Industry for National Defense)
* China National Space Administration
* Japan Aerospace Exploration Agency (Institute of Space and Astronautical Science
* National Aerospace Laboratory of Japan
* National Space Development Agency of Japan)
* National Institute of Information and Communications Technology
* Institute for Unmanned Space Experiment Free Flyer
* National Remote Sensing Center
* Korean Committee of Space Technology
* Korea Aerospace Research Institute
* National Space Organization (Republic of China), National Space Organization
Southeast Asia
* National Institute of Aeronautics and Space
* Malaysian Space Agency
* Philippine Atmospheric, Geophysical and Astronomical Services Administration
* Thai Ministry of Science and Technology's Space Agency
* Space Technology Institute
* Vietnam Space Commission
South Asia
* Space Research and Remote Sensing Organization
* Department of Space
** Antrix Corporation
** Indian Institute of Space Science and Technology
** Indian Space Research Organisation
** National Atmospheric Research Laboratory
** New Space India Limited
** North-Eastern Space Applications Centre
** Physical Research Laboratory
** Semi-Conductor Laboratory
* Space and Upper Atmosphere Research Commission
Southwest Asia
* Azerbaijan National Aerospace Agency
* Iran Aviation Industries Organization
* Iranian Space Agency
* Israel Space Agency
* National Committee for Space Research
* TUBITAK Space Technologies Research Institute, TÜBİTAK UZAY
Central Asia
* KazCosmos
* Kazakh Space Research Institute
* Turkmenistan National Space Agency
* UzbekCosmos
=Europe
=
* Austrian Space Agency
* Belarus Space Agency
* Belgian Institute for Space Aeronomy
* Bulgarian Space Agency
* Czech Space Office
* Danish National Space Center
* esa European Cooperation for Space Standardization
* European Space Agency
* EUMETSAT
* European Union Satellite Centre
* CNES
* German Aerospace Center
* Institute for Space Applications and Remote Sensing
* Hungarian Space Office
* Space Ireland
* Italian Space Agency
* Space Science and Technology Institute
* Luxinnovation
* Netherlands Institute for Space Research
* Norwegian Space Centre
* Space Research Centre
* Portuguese Space Company
* Romanian Space Agency
* Russian Federal Space Agency
* Russian Space Research Institute
* Russian Space Forces
* Soviet space program
* Instituto Nacional de Técnica Aeroespacial
* Swedish National Space Board
* Swiss Space Office
* UK Space Agency
* State Space Agency of Ukraine
=Oceania
=
* Commonwealth Scientific and Industrial Research Organisation
=World
=
* Asia-Pacific Space Cooperation Organization
* Consultative Committee for Space Data Systems
* Committee on Space Research
* International Academy of Astronautics
* International Telecommunications Satellite Organization
* Intercosmos
* Intersputnik
* Pan-Arab Space Agency
* United Nations
** United Nations Committee on the Peaceful Uses of Outer Space
** United Nations Office for Outer Space Affairs
Preceded by the Soviet space program
Tycho Brahe
Tycho Brahe ( ; ; born Tyge Ottesen Brahe, ; 14 December 154624 October 1601), generally called Tycho for short, was a Danish astronomer of the Renaissance, known for his comprehensive and unprecedentedly accurate astronomical observations. He ...
* Annie Jump Cannon
* Alvan Clark
* Nicholas Copernicus
*
Galileo Galilei
Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 – 8 January 1642), commonly referred to as Galileo Galilei ( , , ) or mononymously as Galileo, was an Italian astronomer, physicist and engineer, sometimes described as a poly ...
* George Ellery Hale
* William Herschel
* Edwin Hubble
* Jacobus Kapteyn
* Johannes Kepler
* Gerard Kuiper
* Joseph-Louis Lagrange
* Pierre-Simon Laplace
* Henrietta Leavitt
* Isaac Newton
* Edward C. Pickering
*
Ptolemy
Claudius Ptolemy (; , ; ; – 160s/170s AD) was a Greco-Roman mathematician, astronomer, astrologer, geographer, and music theorist who wrote about a dozen scientific treatises, three of which were important to later Byzantine science, Byzant ...
* Henry Norris Russell
* Harlow Shapley
See also
* Asterism (astronomy), Asterism
*
Constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object.
The first constellati ...
*
Galaxy
A galaxy is a Physical system, system of stars, stellar remnants, interstellar medium, interstellar gas, cosmic dust, dust, and dark matter bound together by gravity. The word is derived from the Ancient Greek, Greek ' (), literally 'milky', ...
Helioseismology
Helioseismology is the study of the structure and dynamics of the Sun through its oscillations. These are principally caused by sound waves that are continuously driven and damped by convection near the Sun's surface. It is similar to geoseismol ...
* Infrared dark cloud
* Intergalactic star
* Open cluster
*
Planet
A planet is a large, Hydrostatic equilibrium, rounded Astronomical object, astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets b ...
* Star cluster
* Stellar association
* Supercluster