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Indus (constellation)
Indus is a constellation in the southern sky first professionally surveyed by Europeans in the 1590s and mapped on a globe by Petrus Plancius by early 1598. It was included on a plate illustrating southern constellations in Johann Bayer, Bayer's sky atlas ''Uranometria'' in 1603. It lies well south of the Tropic of Capricorn but its triangular shape can be seen for most of the year from the Equator. It is elongated from north to south and has a complex boundary. The English translation of its name is generally given as ''the Indian'', though it is unclear which indigenous people the constellation was originally supposed to represent. Features Indus lacks stars among the sky's brightest 100 stars in apparent magnitude. Its brightest stars are two of third magnitude and three of fourth magnitude. Bright stars Alpha Indi, its brightest, is an orange giant of magnitude 3.1, 101 light-years away. Beta Indi is an orange giant of magnitude 3.7, 600 light-years distant. Delta Indi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indigenous Peoples Of The Americas
In the Americas, Indigenous peoples comprise the two continents' pre-Columbian inhabitants, as well as the ethnic groups that identify with them in the 15th century, as well as the ethnic groups that identify with the pre-Columbian population of the Americas as such. These populations exhibit significant diversity; some Indigenous peoples were historically hunter-gatherers, while others practiced agriculture and aquaculture. Various Indigenous societies developed complex social structures, including pre-contact monumental architecture, organized city, cities, city-states, chiefdoms, state (polity), states, monarchy, kingdoms, republics, confederation, confederacies, and empires. These societies possessed varying levels of knowledge in fields such as Pre-Columbian engineering in the Americas, engineering, Pre-Columbian architecture, architecture, mathematics, astronomy, History of writing, writing, physics, medicine, Pre-Columbian agriculture, agriculture, irrigation, geology, minin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tropic Of Capricorn
The Tropic of Capricorn (or the Southern Tropic) is the circle of latitude that contains the subsolar point at the December (or southern) solstice. It is thus the southernmost latitude where the Sun can be seen directly overhead. It also reaches 90 degrees below the horizon at solar midnight on the June Solstice. Its northern equivalent is the Tropic of Cancer. The Tropic of Capricorn is one of the five major circles of latitude marked on maps of Earth. Its latitude is currently south of the Equator, but it is very gradually moving northward, currently at the rate of 0.47 arcseconds, or 15 metres, per year. Name When this line of latitude was named, the Sun was in the constellation Capricornus at the December solstice. This is the date each year when the Sun reaches zenith at this latitude, the southernmost declination it reaches for the year. (Due to the axial precession, precession of the equinoxes the Sun currently appears in Sagittarius (constellation), Sagittarius at t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SETI
Seti or SETI may refer to: Astrobiology * SETI, the search for extraterrestrial intelligence. ** SETI Institute, an astronomical research organization *** SETIcon, a former convention organized by the SETI Institute ** Berkeley SETI Research Center, an astronomical research organization *** SETI@home, a distributed computing project ** Active SETI, the attempt to send messages to intelligent aliens Egyptology * Seti (commander), grandfather of Seti I * Seti (Viceroy of Kush) * Seti I (died 1279 BC), pharaoh * Seti II (died 1197 BC), pharaoh * Seti-Merenptah, a son of Seti II * Seti, son of Amun-her-khepeshef * Sethi, one of List of children of Ramesses II#, the sons of Ramesses II Music * SETI (band), an ambient music band from New York City * SETI (The Kovenant album), ''SETI'' (The Kovenant album), an album by metal band The Kovenant Places * Seti River, a tributary of the Karnali River in Nepal * Seti Gandaki River or Seti River, a tributary of the Trishuli River in Nepal * S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brown Dwarfs
Brown dwarfs are substellar objects that have more mass than the biggest gas giant planets, but less than the least massive main-sequence stars. Their mass is approximately 13 to 80 times that of Jupiter ()not big enough to sustain nuclear fusion of hydrogen into helium in their cores, but massive enough to emit some light and heat from the fusion of deuterium ( 2H). The most massive ones (> ) can fuse lithium ( 7Li). Astronomers classify self-luminous objects by spectral type, a distinction intimately tied to the surface temperature, and brown dwarfs occupy types M (2100–3500 K), L (1300–2100 K), T (600–1300 K), and Y (< 600 K). As brown dwarfs do not undergo stable hydrogen fusion, they cool down over time, progressively passing through later spectral types as they age. Their name comes not from the color of light ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yellow Dwarf 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 star (luminosity class V) of spectral type G. Such a star has about 0.9 to 1.1 solar masses and an effective temperature between about . Like other main-sequence stars, a G-type main-sequence star converts the element hydrogen to helium in its core by means of nuclear fusion. The Sun, the star in the center of the Solar System to which the Earth is gravitationally bound, is an example of a G-type main-sequence star (G2V type). Each second, the Sun fuses approximately 600 million tons of hydrogen into helium in a process known as the proton–proton chain (4 hydrogens form 1 helium), converting about 4 million tons of matter to energy. Besides the Sun, other well-known examples of G-type main-sequence stars include Alpha Centauri, Tau Ceti, and 51 Pegasi. Description The term ''yellow dwarf'' is a misnomer, because G-type stars actually range in col ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orange Dwarf
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 ("red dwarfs") and yellow/white G-type main-sequence stars. They have masses between 0.6 and 0.9 times the mass of the Sun and surface temperatures between 3,900 and 5,300 K. These stars are of particular interest in the search for extraterrestrial life due to their stability and long lifespan. These stars stay on the main sequence for up to 70 billion years, a length of time much larger than the time the universe has existed (13.8 billion years), as such none have had sufficient time to leave the main sequence. Well-known examples include Alpha Centauri B (K1 V), Epsilon Indi (K5 V) and Epsilon Eridani (K2 V). Nomenclature In modern usage, the names applied to K-type main sequence stars vary. When explicitly defined, late K dwarfs are ty ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light Year
A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distance, astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astronomical Union (IAU), a light-year is the distance that Speed of light, light travels in vacuum in one Julian year (astronomy), Julian year (365.25 days). Despite its inclusion of the word "year", the term should not be misinterpreted as a unit of time. The ''light-year'' is most often used when expressing distances to stars and other distances on a Galaxy, galactic scale, especially in public understanding of science, non-specialist contexts and popular science publications. The unit most commonly used in professional astronomy is the parsec (symbol: pc, about 3.26 light-years). Definitions As defined by the International Astronomical Union (IAU), the light-year is the product of the Julian year (astronomy), Julian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 of Earth's water is contained in its global ocean, covering Water distribution on Earth, 70.8% of Earth's crust. The remaining 29.2% of Earth's crust is land, most of which is located in the form of continental landmasses within Earth's land hemisphere. Most of Earth's land is at least somewhat humid and covered by vegetation, while large Ice sheet, sheets of ice at Polar regions of Earth, Earth's polar polar desert, deserts retain more water than Earth's groundwater, lakes, rivers, and Water vapor#In Earth's atmosphere, atmospheric water combined. Earth's crust consists of slowly moving tectonic plates, which interact to produce mountain ranges, volcanoes, and earthquakes. Earth's outer core, Earth has a liquid outer core that generates a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Right-angled Triangle
A right triangle or right-angled triangle, sometimes called an orthogonal triangle or rectangular triangle, is a triangle in which two sides are perpendicular, forming a right angle ( turn or 90 degrees). The side opposite to the right angle is called the ''hypotenuse'' (side c in the figure). The sides adjacent to the right angle are called ''legs'' (or ''catheti'', singular: '' cathetus''). Side a may be identified as the side ''adjacent'' to angle B and ''opposite'' (or ''opposed to'') angle A, while side b is the side adjacent to angle A and opposite angle B. Every right triangle is half of a rectangle which has been divided along its diagonal. When the rectangle is a square, its right-triangular half is isosceles, with two congruent sides and two congruent angles. When the rectangle is not a square, its right-triangular half is scalene. Every triangle whose base is the diameter of a circle and whose apex lies on the circle is a right triangle, with the right angle at th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delta Indi
Delta Indi, Latinized from δ Indi, is a binary star system in the southern constellation of Indus. It is visible to the naked eye with a combined apparent visual magnitude of +4.40. The brighter primary, designated component A, is magnitude 4.80 while the companion, component B, is magnitude 5.96. Based upon an annual parallax shift of 17.34 mas as measured from Earth, the system is located about 188 light years from the Sun. The binary nature of this system was discovered by South African astronomer William Stephen Finsen from 1936 onward, with his published orbital elements appearing in 1956. The pair have an orbital period of 12.2 years, a semimajor axis of 0.176 arc seconds, and an eccentricity of around 0.03. They have been listed with a 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Indi
Beta Indi, Latinized from β Indi, is the second brightest star in the southern constellation of Indus. It is visible to the naked eye as a faint, orange-hued point of light with an apparent visual magnitude of 3.67. The star is located approximately 600 light years from the Sun, based on parallax, but is drifting closer with a radial velocity of −5 km/s. The stellar classification of this star is K1II, matching an evolved bright giant. Earlier it had been categorized as an ordinary giant with a class of K0III. It is a hybrid giant with both a hot stellar corona and cool stellar winds, and is a weak X-ray source with a flux measured at . Having consumed the supply of hydrogen at its core, this star has expanded off the main sequence and now has about 56 times the girth of the Sun. It is 53 million years old with 6.7 times the mass of the Sun. The star is radiating 1,183 times the Sun's luminosity from its enlarged photosphere at an effect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orange 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 Hertzsprung–Russell diagram and correspond to luminosity classes II and III. The terms ''giant'' and ''dwarf'' were coined for stars of quite different luminosity despite similar temperature or spectral type (namely K and M) by Ejnar Hertzsprung in 1905 or 1906. Giant stars have radii up to a few hundred times the Sun and luminosities over 10 times that of the Sun. Stars still more luminous than giants are referred to as supergiants and hypergiants. A hot, luminous main-sequence star may also be referred to as a giant, but any main-sequence star is properly called a dwarf, regardless of how large and luminous it is. Formation A star becomes a giant after all the hydrogen available for fusion at its core has been depleted and, as a result ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
