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Venus is the second
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 ...
from 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 ...
. It is often called
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 ...
's "twin" or "sister" planet for having almost the same size and mass, and the closest orbit to Earth's. While both are
rocky planet A terrestrial planet, tellurian planet, telluric planet, or rocky planet, is a planet that is composed primarily of silicate, rocks or metals. Within the Solar System, the terrestrial planets accepted by the IAU are the inner planets closest to ...
s, Venus has an
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 ...
much thicker and denser than Earth and any other rocky body in the
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 ...
. Its atmosphere is composed of mostly
carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
(), with a global
sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen, ...
cloud cover and no
liquid water Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known living organisms ( ...
. At the mean surface level the atmosphere reaches a temperature of and a
pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and eve ...
92 times greater than Earth's at sea level, turning the lowest layer of the atmosphere into a
supercritical fluid A supercritical fluid (SCF) is a substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist, but below the pressure required to compress it into a solid. It can effuse through porous sol ...
. Venus is the third brightest object in Earth's sky, after the
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 ...
and the Sun, and, like Mercury, appears always relatively close to the Sun, either as a "morning star" or an "evening star", resulting from orbiting closer ( inferior) to the Sun than Earth. The orbits of Venus and Earth make the two planets approach each other in
synodic period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets, ...
s of 1.6 years. In the course of this Venus comes closer to Earth than any other planet, while on average Mercury stays closer to Earth (and any other planet) due to its more inferior orbit. Venus is frequently used for
gravity assist A gravity assist, gravity assist maneuver, swing-by, or generally a gravitational slingshot in orbital mechanics, is a type of spaceflight flyby (spaceflight), flyby which makes use of the relative movement (e.g. orbit around the Sun) and gra ...
s, as a waypoint for interplanetary flights. Venus has no
moons 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 deriva ...
and has a very slow
retrograde Retrograde may refer to: Film and television * Retrograde (2004 film), ''Retrograde'' (2004 film), a film by Christopher Kulikowski * Retrograde (2022 American film), ''Retrograde'' (2022 American film), a documentary film by Matthew Heineman * ...
rotation about its axis, a result of competing forces of solar tidal locking and differential heating of Venus's massive atmosphere. As a result a Venusian day is 116.75 Earth days long, about half a Venusian
solar year A tropical year or solar year (or tropical period) is the time that the Sun takes to return to the same position in the sky – as viewed from the Earth or another celestial body of the Solar System – thus completing a full cycle of astronom ...
, which is 224.7 Earth days long. Venus has a weak magnetosphere, lacking an internal dynamo it is induced by the
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 ...
and the atmosphere interacting. Internally, Venus has a
core Core or cores may refer to: Science and technology * Core (anatomy), everything except the appendages * Core (laboratory), a highly specialized shared research resource * Core (manufacturing), used in casting and molding * Core (optical fiber ...
mantle, and  crust.
Internal heat Internal heat is the heat source from the interior of celestial objects, such as stars, brown dwarfs, planets, moons, dwarf planets, and (in the early history of the Solar System) even asteroids such as Vesta, resulting from contraction caused ...
escapes through active volcanism, resulting in resurfacing instead of
plate tectonics Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed durin ...
. Venus may have had liquid surface water early in its history with a habitable environment, before a
runaway greenhouse effect A runaway greenhouse effect will occur when a planet's atmosphere contains greenhouse gas in an amount sufficient to block thermal radiation from leaving the planet, preventing the planet from cooling and from having liquid water on its surface. ...
evaporated any water and turned Venus into its present state. Conditions at the cloud layer of Venus have been identified as possibly favourable for
life on Venus The possibility of life on Venus is a subject of interest in astrobiology due to Venus's proximity and similarities to Earth. To date, no definitive evidence has been found of past or present life there. In the early 1960s, studies conducted vi ...
, with possible biomarkers having been found in 2020, which has spurred new research and missions to Venus. Humans have been observing Venus throughout history across the globe, featuring it and its prominence in fiction, mythology, astrology and astronomy, acquiring particular importance in many cultures. With telescopes the
phases of Venus The phases of Venus are the variations of lighting seen on the planet's surface, similar to lunar phases. The first recorded observations of them are thought to have been telescopic observations by Galileo Galilei in 1610. Although the extreme c ...
became discernable and were in 1613 soon presented as decisive evidence disproving the then dominant
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 ...
and supporting the
heliocentric model 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 th ...
. In 1961 Venus became the target of the first interplanetary space flight (
Venera 1 ''Venera 1'' ( meaning ''Venus 1''), also known as Venera-1VA No.2 and occasionally in the West as ''Sputnik 8'', was the first spacecraft to perform an interplanetary flight and the first to fly past Venus, as part of the Soviet Union's Venera ...
), while only the second interplanetary probe returned data, passing Venus the next year (
Mariner 2 Mariner 2 (Mariner-Venus 1962), an American space probe to Venus, was the first robotic space probe to report successfully from a planetary encounter. The first successful spacecraft in the NASA Mariner program, it was a simplified version of t ...
). Venus also became the first planet other than Earth to be impacted (1967,
Venera 4 Venera 4 (), also designated 4V-1 No.310, was a probe in the Soviet Venera program for the exploration of Venus. The probe comprised a lander, designed to enter the Venusian atmosphere and parachute to the surface, and a carrier/ flyby space ...
) and landed on (1970,
Venera 7 Venera 7 () was a Soviet spacecraft, part of the Venera series of probes to Venus. When it landed on the Venusian surface on 15 December 1970, it became the first spacecraft to soft land on another planet and the first to transmit data from the ...
). The data returned revealed a planet with a thick atmosphere and its resulting infernal
greenhouse effect The greenhouse effect occurs when greenhouse gases in a planet's atmosphere insulate the planet from losing heat to space, raising its surface temperature. Surface heating can happen from an internal heat source (as in the case of Jupiter) or ...
, raising concerns about
global warming Present-day climate change includes both global warming—the ongoing increase in global average temperature—and its wider effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes ...
and
climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...
on Earth. the only probe active and reaching Venus is the
Solar Orbiter The Solar Orbiter (SolO) is a Sun-observing probe developed by the European Space Agency (ESA) with a National Aeronautics and Space Administration (NASA) contribution. Solar Orbiter, designed to obtain detailed measurements of the inner heli ...
, performing flybys until 2030. The next planned Venus mission is not set to launch before summer 2026 (
Venus Life Finder Venus Life Finder is a planned Venus space probe designed to detect Life on Venus, signs of life in the Atmosphere of Venus, Venusian atmosphere. Slated to be the first Private spaceflight, private mission to another planet, the spacecraft is b ...
).


Physical characteristics

Venus is one of the four
terrestrial planet A terrestrial planet, tellurian planet, telluric planet, or rocky planet, is a planet that is composed primarily of silicate, rocks or metals. Within the Solar System, the terrestrial planets accepted by the IAU are the inner planets closest to ...
s in the Solar System, meaning that it is a rocky body like Earth. It is similar to Earth in size and mass and is often described as Earth's "sister" or "twin". Venus is very close to spherical due to its slow rotation. It has a diameter of —only less than Earth's—and its mass is 81.5% of Earth's, making it the third-smallest planet in the
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 ...
. Conditions on the surface of Venus differ radically from those on Earth because its dense
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 ...
is 96.5% carbon dioxide, causing an intense
greenhouse effect The greenhouse effect occurs when greenhouse gases in a planet's atmosphere insulate the planet from losing heat to space, raising its surface temperature. Surface heating can happen from an internal heat source (as in the case of Jupiter) or ...
, with most of the remaining 3.5% being
nitrogen Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...
. The surface pressure is , and the average surface temperature is , above the critical points of both major constituents and making the surface atmosphere a
supercritical fluid A supercritical fluid (SCF) is a substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist, but below the pressure required to compress it into a solid. It can effuse through porous sol ...
of mainly
supercritical carbon dioxide Supercritical carbon dioxide (s) is a fluid state of carbon dioxide where it is held at or above its critical temperature and critical pressure. Carbon dioxide usually behaves as a gas in air at standard temperature and pressure (STP), or a ...
and some supercritical nitrogen.


Geography

The Venusian surface was a subject of speculation until some of its secrets were revealed by probes in the 20th century. ''
Venera The Venera (, 'Venus') program was a series of space probes developed by the Soviet Union between 1961 and 1984 to gather information about the planet Venus. Thirteen probes successfully entered the Venusian atmosphere, including the two ...
'' landers in 1975 and 1982 returned images of a surface covered in sediment and relatively angular rocks. The surface was mapped in detail by ''Magellan'' in 1990–91. There is evidence of extensive volcanism, and variations in the atmospheric
sulphur dioxide Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a colorless gas with a pungent smell that is responsible for the odor of burnt matches. It is r ...
may indicate that there are active volcanoes. About 80% of the Venusian surface is covered by smooth, volcanic plains, consisting of 70% plains with wrinkle ridges and 10% smooth or lobate plains. Two highland "continents" make up the rest of its surface area, one lying in the planet's northern hemisphere and the other just south of the equator. The northern continent is called
Ishtar Terra Ishtar Terra is the second largest of the three continental terrae regions on the planet Venus, the others being Aphrodite Terra and Lada Terra. It is a highland region named after the Akkadian goddess Ishtar, and is found in the north o ...
after
Ishtar Inanna is the List of Mesopotamian deities, ancient Mesopotamian goddess of war, love, and fertility. She is also associated with political power, divine law, sensuality, and procreation. Originally worshipped in Sumer, she was known by the Akk ...
, the
Babylon Babylon ( ) was an ancient city located on the lower Euphrates river in southern Mesopotamia, within modern-day Hillah, Iraq, about south of modern-day Baghdad. Babylon functioned as the main cultural and political centre of the Akkadian-s ...
ian goddess of love, and is about the size of Australia. The
Maxwell Montes Maxwell Montes is a mountain range on the planet Venus, of which Skadi Mons is the List of tallest mountains in the Solar System, highest. General description Located on Ishtar Terra, the more northern of the planet's two major highlands, Ma ...
mountain range lies on Ishtar Terra. Its peak is the highest point on Venus, above the Venusian average surface elevation. The southern continent is called
Aphrodite Terra Aphrodite Terra is one of the three continental regions on the planet Venus, the others being Ishtar Terra and Lada Terra. It is named for Aphrodite, the Greek equivalent of the goddess Venus, and is found near the equator of the planet. Aphro ...
, after the
Greek mythological Greek mythology is the body of myths originally told by the ancient Greeks, and a genre of ancient Greek folklore, today absorbed alongside Roman mythology into the broader designation of classical mythology. These stories concern the ancient ...
goddess of love, and is the larger of the two highland regions at roughly the size of South America. A network of fractures and faults covers much of this area. There is recent evidence of
lava Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...
flow on Venus (2024), such as flows on
Sif Mons Sif Mons is an active shield volcano located in Eistla Regio on Venus. It has a diameter of and a height of . The volcano is one of the few identified active extraterrestrial volcanoes, having last erupted between 1990 and 1992. It is named af ...
, a shield volcano, and on
Niobe Planitia Venus, the second planet from the Sun, is classified as a terrestrial planet. It is sometimes called Earth's "sister planet" due to their similar size, gravity, and bulk composition (Venus is both the closest planet to Earth and the planet closest ...
, a flat plain. There are visible
caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...
s. The planet has few
impact crater An impact crater is a depression (geology), depression in the surface of a solid astronomical body formed by the hypervelocity impact event, impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal c ...
s, demonstrating that the surface is relatively young, at 300–600million years old. Venus has some unique surface features in addition to the impact craters, mountains, and valleys commonly found on rocky planets. Among these are flat-topped volcanic features called " farra", which look somewhat like pancakes and range in size from across, and from high; radial, star-like fracture systems called "novae"; features with both radial and concentric fractures resembling spider webs, known as " arachnoids"; and "coronae", circular rings of fractures sometimes surrounded by a depression. These features are volcanic in origin. Most Venusian surface features are named after historical and mythological women. Exceptions are Maxwell Montes, named after
James Clerk Maxwell James Clerk Maxwell (13 June 1831 – 5 November 1879) was a Scottish physicist and mathematician who was responsible for the classical theory of electromagnetic radiation, which was the first theory to describe electricity, magnetism an ...
, and highland regions Alpha Regio,
Beta Regio Beta Regio is a region of the planet Venus known as a ''volcanic rise''. Measuring about in extent, it constitutes a prominent upland region of Venus centered at . The first features that showed up in early radar surveys of the planet were give ...
, and
Ovda Regio Ovda Regio is a Venusian crustal plateau located near the equator in the western highland region of Aphrodite Terra that stretches from 10°N to 15°S and 50°E to 110°E. Known as the largest crustal plateau in Venus, the regio covers an area of ...
. The last three features were named before the current system was adopted by the
International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...
, the body which oversees
planetary nomenclature Planetary nomenclature, like terrestrial nomenclature, is a system of uniquely identifying features on the surface of a planet or natural satellite so that the features can be easily located, described, and discussed. Since the invention of the ...
. The longitude of physical features on Venus is expressed relative to its
prime meridian A prime meridian is an arbitrarily chosen meridian (geography), meridian (a line of longitude) in a geographic coordinate system at which longitude is defined to be 0°. On a spheroid, a prime meridian and its anti-meridian (the 180th meridian ...
. The original prime meridian passed through the radar-bright spot at the centre of the oval feature Eve, located south of Alpha Regio. After the Venera missions were completed, the prime meridian was redefined to pass through the central peak in the crater
Ariadne In Greek mythology, Ariadne (; ; ) was a Cretan princess, the daughter of King Minos of Crete. There are variations of Ariadne's myth, but she is known for helping Theseus escape from the Minotaur and being abandoned by him on the island of N ...
on
Sedna Planitia Sedna Planitia is a large lowland area of 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 r ...
. The stratigraphically oldest tessera terrains have consistently lower thermal emissivity than the surrounding basaltic plains measured by ''
Venus Express ''Venus Express'' (VEX) was the first Venus exploration mission of the European Space Agency (ESA). Launched in November 2005, it arrived at Venus in April 2006 and began continuously sending back science data from its polar orbit around Venus. ...
'' and ''Magellan'', indicating a different, possibly a more
felsic In geology, felsic is a grammatical modifier, modifier describing igneous rocks that are relatively rich in elements that form feldspar and quartz.Marshak, Stephen, 2009, ''Essentials of Geology,'' W. W. Norton & Company, 3rd ed. It is contrasted ...
, mineral assemblage. The mechanism to generate a large amount of felsic crust usually requires the presence of a water ocean and
plate tectonics Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed durin ...
, implying that habitable condition existed on early Venus, with large bodies of water at some point. However, the nature of tessera terrains is far from certain. Studies reported in 2023 suggested for the first time that Venus may have had
plate tectonics Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed durin ...
during ancient times and, as a result, may have had a more habitable environment, possibly one capable of sustaining
life Life, also known as biota, refers to matter that has biological processes, such as Cell signaling, signaling and self-sustaining processes. It is defined descriptively by the capacity for homeostasis, Structure#Biological, organisation, met ...
. Venus has gained interest as a case for research into the development of Earth-like planets and their habitability.


Volcanism

Much of the Venusian surface appears to have been shaped by volcanic activity. Venus has several times as many volcanoes as Earth, and it has 167 large volcanoes that are over across. The only volcanic complex of this size on Earth is the Big Island of Hawaii. More than 85,000 volcanoes on Venus have been identified and mapped. This is not because Venus is more volcanically active than Earth, but because its crust is older and is not subject to the
erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...
processes active on Earth. Earth's
oceanic crust Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramaf ...
is continually recycled by
subduction Subduction is a geological process in which the oceanic lithosphere and some continental lithosphere is recycled into the Earth's mantle at the convergent boundaries between tectonic plates. Where one tectonic plate converges with a second p ...
at the boundaries of tectonic plates, and has an average age of about 100 million years, whereas the Venusian surface is estimated to be 300–600million years old. Several lines of evidence point to ongoing
volcanic A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often fo ...
activity on Venus. Sulfur dioxide concentrations in the upper atmosphere dropped by a factor of 10 between 1978 and 1986, jumped in 2006, and again declined 10-fold. This may mean that levels were boosted several times by large volcanic eruptions. It has been suggested that Venusian lightning (discussed below) could originate from volcanic activity (i.e.
volcanic lightning Volcanic lightning is an electrical discharge caused by a volcanic eruption rather than from an ordinary thunderstorm. Volcanic lightning arises from colliding, fragmenting particles of volcanic ash (and sometimes ice), which generate static elec ...
). In January 2020, astronomers reported evidence suggesting that Venus is currently volcanically active, specifically the detection of
olivine The mineral olivine () is a magnesium iron Silicate minerals, silicate with the chemical formula . It is a type of Nesosilicates, nesosilicate or orthosilicate. The primary component of the Earth's upper mantle (Earth), upper mantle, it is a com ...
, a volcanic product that would weather quickly on the planet's surface. This massive volcanic activity is fuelled by a hot interior, which models say could be explained by energetic collisions when the planet was young, as well as
radioactive decay Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is conside ...
as in the case of the earth. Impacts would have had significantly higher velocity than on Earth, both because Venus moves faster due to its closer proximity to the Sun and because high-eccentricity objects colliding with the planet would have high speeds. In 2008 and 2009, the first direct evidence for ongoing volcanism was observed by ''Venus Express'', in the form of four transient localized infrared hot spots within the rift zone Ganis Chasma, near the shield volcano
Maat Mons Maat Mons is a massive Venusian shield volcano on the planet Venus and the planet's second-highest mountain and highest volcano. It rises above the mean planetary radius at , and nearly 5 km above the surrounding plains. It is named after t ...
. Three of the spots were observed in more than one successive orbit. These spots are thought to represent lava freshly released by volcanic eruptions. The actual temperatures are not known, because the size of the hot spots could not be measured, but are likely to have been in the range, relative to a normal temperature of . In 2023, scientists reexamined topographical images of the Maat Mons region taken by the ''
Magellan Ferdinand Magellan ( – 27 April 1521) was a Portuguese people, Portuguese explorer best known for having planned and led the Magellan expedition, 1519–22 Spanish expedition to the East Indies. During this expedition, he also discovered t ...
'' orbiter. Using computer simulations, they determined that the topography had changed during an 8-month interval, and concluded that active volcanism was the cause.


Craters

There are almost a thousand impact craters on Venus, evenly distributed across its surface. On other cratered bodies, such as Earth and the Moon, craters show a range of states of degradation. On the Moon, degradation is caused by subsequent impacts, whereas on Earth it is caused by wind and rain erosion. On Venus, about 85% of the craters are in pristine condition. The number of craters, together with their well-preserved condition, indicates the planet underwent a global resurfacing event 300–600million years ago, followed by a decay in volcanism. Whereas Earth's crust is in continuous motion, Venus is thought to be unable to sustain such a process. Without plate tectonics to dissipate heat from its mantle, Venus instead undergoes a cyclical process in which mantle temperatures rise until they reach a critical level that weakens the crust. Then, over a period of about 100million years, subduction occurs on an enormous scale, completely recycling the crust. Venusian craters range from in diameter. No craters are smaller than 3km, because of the effects of the dense atmosphere on incoming objects. Objects with less than a certain
kinetic energy In physics, the kinetic energy of an object is the form of energy that it possesses due to its motion. In classical mechanics, the kinetic energy of a non-rotating object of mass ''m'' traveling at a speed ''v'' is \fracmv^2.Resnick, Rober ...
are slowed so much by the atmosphere that they do not create an impact crater. Incoming projectiles less than in diameter will fragment and burn up in the atmosphere before reaching the ground.


Internal structure

Without data from
reflection seismology Reflection seismology (or seismic reflection) is a method of exploration geophysics that uses the principles of seismology to estimate the properties of the Earth's subsurface from reflection (physics), reflected seismic waves. The method requir ...
or knowledge of its
moment of inertia The moment of inertia, otherwise known as the mass moment of inertia, angular/rotational mass, second moment of mass, or most accurately, rotational inertia, of a rigid body is defined relatively to a rotational axis. It is the ratio between ...
, little direct information has been available about the internal structure and
geochemistry Geochemistry is the science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems such as the Earth's crust and its oceans. The realm of geochemistry extends beyond the Earth, encompassing the e ...
of Venus. The similarity in size and density between Venus and Earth suggests that they share a similar internal structure: a
core Core or cores may refer to: Science and technology * Core (anatomy), everything except the appendages * Core (laboratory), a highly specialized shared research resource * Core (manufacturing), used in casting and molding * Core (optical fiber ...
, mantle, and crust. Like that of Earth, the Venusian core is most likely at least partially liquid because the two planets have been cooling at about the same rate, although a completely solid core cannot be ruled out. The slightly smaller size of Venus means pressures are 24% lower in its deep interior than Earth's. The predicted values for the moment of inertia based on planetary models suggest a core radius of 2,900–3,450 km. There is now an estimate of 3,500 km from the
moment of inertia The moment of inertia, otherwise known as the mass moment of inertia, angular/rotational mass, second moment of mass, or most accurately, rotational inertia, of a rigid body is defined relatively to a rotational axis. It is the ratio between ...
based on the rate of
axial precession In astronomy, axial precession is a gravity-induced, slow, and continuous change in the orientation of an astronomical body's rotational axis. In the absence of precession, the astronomical body's orbit would show axial parallelism. In parti ...
, measured between 2006 and 2020. The crust of Venus is estimated to be 40 kilometers thick on average and at most 65 kilometers thick. The principal difference between the two planets is the lack of evidence for plate tectonics on Venus, possibly because its crust is too strong to
subduct Subduction is a geological process in which the oceanic lithosphere and some continental lithosphere is recycled into the Earth's mantle at the convergent boundaries between tectonic plates. Where one tectonic plate converges with a second plat ...
without water to make it less
viscous Viscosity is a measure of a fluid's rate-dependent resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for example, syrup h ...
. This results in reduced heat loss from the planet, preventing it from cooling and providing a likely explanation for its lack of an internally generated
magnetic field A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular ...
. Instead, Venus may lose its internal heat in periodic major resurfacing events.


Magnetic field and core

In 1967, ''
Venera 4 Venera 4 (), also designated 4V-1 No.310, was a probe in the Soviet Venera program for the exploration of Venus. The probe comprised a lander, designed to enter the Venusian atmosphere and parachute to the surface, and a carrier/ flyby space ...
'' found Venus's
magnetic field A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular ...
to be much weaker than that of Earth. This magnetic field is induced by an interaction between the
ionosphere The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays ...
and the
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 ...
, rather than by an internal
dynamo "Dynamo Electric Machine" (end view, partly section, ) A dynamo is an electrical generator that creates direct current using a commutator. Dynamos employed electromagnets for self-starting by using residual magnetic field left in the iron cores ...
as in the Earth's
core Core or cores may refer to: Science and technology * Core (anatomy), everything except the appendages * Core (laboratory), a highly specialized shared research resource * Core (manufacturing), used in casting and molding * Core (optical fiber ...
. Venus's small induced magnetosphere provides negligible protection to the atmosphere against
solar Solar may refer to: Astronomy * Of or relating to the Sun ** Solar telescope, a special purpose telescope used to observe the Sun ** A device that utilizes solar energy (e.g. "solar panels") ** Solar calendar, a calendar whose dates indicate t ...
and
cosmic radiation 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 Sol ...
. The lack of an intrinsic magnetic field on Venus was surprising, given that it is similar to Earth in size and was expected to contain a dynamo at its core. A dynamo requires three things: a
conducting Conducting is the art of directing a musical performance, such as an orchestral or Choir, choral concert. It has been defined as "the art of directing the simultaneous performance of several players or singers by the use of gesture." The primary d ...
liquid, rotation, and
convection Convection is single or Multiphase flow, multiphase fluid flow that occurs Spontaneous process, spontaneously through the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoy ...
. The core is thought to be electrically conductive and, although its rotation is often thought to be too slow, simulations show it is adequate to produce a dynamo. This implies that the dynamo is missing because of a lack of convection in Venus's core. On Earth, convection occurs in the liquid outer layer of the core because the bottom of the liquid layer is much higher in temperature than the top. On Venus, a global resurfacing event may have shut down plate tectonics and led to a reduced
heat flux In physics and engineering, heat flux or thermal flux, sometimes also referred to as heat flux density, heat-flow density or heat-flow rate intensity, is a flow of energy per unit area per unit time (physics), time. Its SI units are watts per sq ...
through the crust. This insulating effect would cause the mantle temperature to increase, thereby reducing the heat flux out of the core. As a result, no internal geodynamo is available to drive a magnetic field. Instead, the heat from the core is reheating the crust. One possibility is that Venus has no solid inner core, or that its core is not cooling, so that the entire liquid part of the core is at approximately the same temperature. Another possibility is that its core has already been completely solidified. The state of the core is highly dependent on the concentration of
sulphur Sulfur (American spelling and the preferred IUPAC name) or sulphur (English in the Commonwealth of Nations, Commonwealth spelling) is a chemical element; it has Symbol (chemistry), symbol S and atomic number 16. It is abundance of the chemical ...
, which is unknown at present. Another possibility is that the absence of a large impact on Venus (''contra'' the Earth's "Moon-forming" impact) left the core of Venus stratified from the core's incremental formation, and without the forces to initiate/sustain convection, and thus a "geodynamo". The weak magnetosphere around Venus means that the solar wind interacts directly with its outer atmosphere. Here, ions of hydrogen and oxygen are being created by the dissociation of water molecules due to
ultraviolet Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of ...
radiation. The solar wind then supplies energy that gives some of these ions sufficient speed to escape Venus's gravity field. This erosion process results in a steady loss of low-mass hydrogen, helium, and oxygen ions, whereas higher-mass molecules, such as carbon dioxide, are more likely to be retained. Atmospheric erosion by the solar wind could have led to the loss of most of Venus's water during the first billion years after it formed. However, the planet may have retained a dynamo for its first 2–3 billion years, so the water loss may have occurred more recently. The erosion has increased the ratio of higher-mass
deuterium Deuterium (hydrogen-2, symbol H or D, also known as heavy hydrogen) is one of two stable isotopes of hydrogen; the other is protium, or hydrogen-1, H. The deuterium nucleus (deuteron) contains one proton and one neutron, whereas the far more c ...
to lower-mass hydrogen in the atmosphere 100 times compared to the rest of the solar system.


Atmosphere and climate

Venus has a dense
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 ...
composed of 96.5%
carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
, 3.5% nitrogen—both exist as supercritical fluids at the planet's surface with a density 6.5% that of water—and traces of other gases including
sulphur dioxide Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a colorless gas with a pungent smell that is responsible for the odor of burnt matches. It is r ...
. The mass of its atmosphere is 92 times that of Earth's, whereas the pressure at its surface is about 93 times that at Earth's—a pressure equivalent to that at a depth of nearly under Earth's ocean surfaces. The density at the surface is , 6.5% that of water or 50 times as dense as Earth's atmosphere at at sea level. The -rich atmosphere generates the strongest
greenhouse effect The greenhouse effect occurs when greenhouse gases in a planet's atmosphere insulate the planet from losing heat to space, raising its surface temperature. Surface heating can happen from an internal heat source (as in the case of Jupiter) or ...
in the Solar System, creating surface temperatures of at least . This makes the Venusian surface hotter than Mercury's, which has a minimum surface temperature of and maximum surface temperature of , even though Venus is nearly twice Mercury's distance from the Sun and thus receives only around a quarter of Mercury's solar
irradiance In radiometry, irradiance is the radiant flux ''received'' by a ''surface'' per unit area. The SI unit of irradiance is the watt per square metre (symbol W⋅m−2 or W/m2). The CGS unit erg per square centimetre per second (erg⋅cm−2⋅s−1) ...
, of 2,600 W/m2 (double that of Earth). Because of its
runaway greenhouse effect A runaway greenhouse effect will occur when a planet's atmosphere contains greenhouse gas in an amount sufficient to block thermal radiation from leaving the planet, preventing the planet from cooling and from having liquid water on its surface. ...
, Venus has been identified by scientists such as
Carl Sagan Carl Edward Sagan (; ; November 9, 1934December 20, 1996) was an American astronomer, planetary scientist and science communicator. His best known scientific contribution is his research on the possibility of extraterrestrial life, including e ...
as a warning and research object linked to
climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...
on Earth. Therefore Venus has been called a greenhouse planet, a planet under a greenhouse inferno. Venus's atmosphere is rich in primordial
noble gas The noble gases (historically the inert gases, sometimes referred to as aerogens) are the members of Group (periodic table), group 18 of the periodic table: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn) and, in some ...
es compared to that of Earth. This enrichment indicates an early divergence from Earth in evolution. An unusually large comet impact or accretion of a more massive
primary atmosphere A primary atmosphere, often called a primordial or proto-atmosphere, is an atmosphere of a protoplanet that forms by Accretion (astrophysics), accretion of Gas, gaseous matter from the protoplanetary disk. Gas giant planets including Jupiter, Satu ...
from the solar nebula have been proposed to explain the enrichment. However, the atmosphere is poor in radiogenic
argon-40 Argon (Ar) has 26 known isotopes, from Ar to Ar, of which three are stable (Ar, Ar, and Ar). On Earth, Ar makes up 99.6% of natural argon. The longest-lived radioactive isotopes are Ar with a half-life of 268 years, Ar with a half-life of 32.9 ye ...
, a proxy for mantle degassing, suggesting an early shutdown of major magmatism. Studies have suggested that billions of years ago, the atmosphere of Venus may have been much more like the one surrounding the early Earth, and there may have been substantial quantities of liquid water on the surface. After a period of 600 million to several billion years, the rising luminosity of the Sun and possibly large volcanic resurfacing caused the evaporation of the original water. A runaway greenhouse effect was created once a critical level of greenhouse gases (including water) was reached in the atmosphere. Although the surface conditions on Venus are no longer hospitable to any terrestrial-like life that might have formed before this event, there is speculation that life may exist in the upper cloud layers of Venus, above the surface, where atmospheric conditions are the most Earth-like in the Solar System, with temperatures ranging between , and the pressure and radiation being about the same as at Earth's surface, but with acidic clouds and the carbon dioxide air. More specifically, between heights of 48 and 59 km temperature and radiation conditions are suitable for life. At lower elevations water would evaporate and at higher elevation UV radiation would be too strong. The putative detection of an
absorption line Absorption spectroscopy is spectroscopy that involves techniques that measure the absorption (electromagnetic radiation), absorption of electromagnetic radiation, as a function of frequency or wavelength, due to its interaction with a sample. Th ...
of
phosphine Phosphine (IUPAC name: phosphane) is a colorless, flammable, highly toxic compound with the chemical formula , classed as a pnictogen hydride. Pure phosphine is odorless, but technical grade samples have a highly unpleasant odor like rotting ...
in Venus's atmosphere, with no known pathway for abiotic production, led to speculation in September 2020 that there could be extant life currently present in the atmosphere. Later research attributed the spectroscopic signal that was interpreted as phosphine to sulphur dioxide, or found that in fact there was no absorption line.
Thermal inertia Thermal inertia is a term commonly used to describe the observed delays in a body's temperature response during heat transfers. The phenomenon exists because of a body's ability to both store and transport heat relative to its environment. Sinc ...
and the transfer of heat by winds in the lower atmosphere mean that the surface temperature does not vary significantly between the hemispheres facing and not facing the Sun, despite Venus's slow rotation. Winds at the surface are slow, moving at a few kilometres per hour, but because of the high density of the atmosphere at the surface, they exert a significant amount of force against obstructions, and transport dust and small stones across the surface. This alone would make it difficult for a human to walk through, even without the heat, pressure, and lack of oxygen. Above the dense layer are thick clouds 45 to 70 km above the surface, consisting mainly of
sulphuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen, and hydrogen, with the molecular formu ...
, which is formed by a reaction catalyzed by UV radiation from sulphur dioxide molecules and then water, resulting in sulphuric acid hydrate. Additionally, the clouds contain approximately 1%
ferric chloride Iron(III) chloride describes the inorganic compounds with the formula (H2O)x. Also called ferric chloride, these compounds are some of the most important and commonplace compounds of iron. They are available both in anhydrous and in hydrated f ...
. Other possible constituents of the cloud particles are
ferric sulfate Iron(III) sulfate or ferric sulfate (British English: sulphate instead of sulfate) is a family of inorganic compounds with the formula Fe2(SO4)3(H2O)n. A variety of water of crystallization, hydrates are known, including the most commonly encount ...
,
aluminium chloride Aluminium chloride, also known as aluminium trichloride, is an inorganic compound with the formula . It forms a hexahydrate with the formula , containing six water molecules of hydration. Both the anhydrous form and the hexahydrate are col ...
and phosphoric anhydride. Clouds at different levels have different compositions and particle size distributions. These clouds reflect, like thick cloud cover on Earth, about 70% of the sunlight that falls on them back into space, and since they cover the whole planet they prevent visual observation of the surface. The permanent cloud cover means that although Venus is closer than Earth to the Sun, it receives less sunlight on the ground, with only 10% of the received sunlight reaching the surface, resulting in average daytime levels of illumination at the surface of 14,000
lux The lux (symbol: lx) is the unit of illuminance, or luminous flux per unit area, in the International System of Units (SI). It is equal to one lumen per square metre. In photometry, this is used as a measure of the irradiance, as perceived by ...
, comparable to that on Earth "in the daytime with overcast clouds". Strong winds at the cloud tops go around Venus about every four to five Earth days. Winds on Venus move at up to 60 times the speed of its rotation, whereas Earth's fastest winds are only 10–20% rotation speed. Although Venus looks featureless in visible light, there are bands or streaks in the UV, whose origin has not been pinned down. The absorption of UV may be due to a compound of oxygen and sulfur, OSSO, which has a double bond between the sulfur atoms and exists in "cis" and "trans" forms, or due to polysulfur compounds from to . The surface of Venus is effectively
isothermal An isothermal process is a type of thermodynamic process in which the temperature ''T'' of a system remains constant: Δ''T'' = 0. This typically occurs when a system is in contact with an outside thermal reservoir, and a change in the sys ...
; it retains a constant temperature not only between the two hemispheres but between the equator and the poles. Venus's minute
axial tilt In astronomy, axial tilt, also known as obliquity, is the angle between an object's rotational axis and its orbital axis, which is the line perpendicular to its orbital plane; equivalently, it is the angle between its equatorial plane and orbita ...
—less than 3°, compared to 23° on Earth—also minimizes seasonal temperature variation. Altitude is one of the few factors that affect Venusian temperatures. The highest point on Venus,
Maxwell Montes Maxwell Montes is a mountain range on the planet Venus, of which Skadi Mons is the List of tallest mountains in the Solar System, highest. General description Located on Ishtar Terra, the more northern of the planet's two major highlands, Ma ...
, is therefore the coolest point on Venus, with a temperature of about and an atmospheric pressure of about . In 1995, the ''Magellan'' spacecraft imaged a highly reflective substance at the tops of the highest mountain peaks, a "
Venus snow Venus snow is a brightening of the radar reflection from the surface of Venus at high elevations. The "snow" appears to be a mineral condensate of lead(II) sulfide and bismuth sulfide precipitated from the atmosphere at altitudes above . The na ...
" that bore a strong resemblance to terrestrial snow. This substance likely formed by a similar process to snow, albeit at a far higher temperature. Too volatile to condense on the surface, it rose in gaseous form to higher elevations, where it is cooler and could precipitate. The identity of this substance is not known with certainty, but speculation has ranged from elemental
tellurium Tellurium is a chemical element; it has symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionally fou ...
to lead sulfide (
galena Galena, also called lead glance, is the natural mineral form of lead(II) sulfide (PbS). It is the most important ore of lead and an important source of silver. Galena is one of the most abundant and widely distributed sulfide minerals. It crysta ...
). Although Venus has no seasons, in 2019 astronomers identified a cyclical variation in sunlight absorption by the atmosphere, possibly caused by opaque, absorbing particles suspended in the upper clouds. The variation causes observed changes in the speed of Venus's zonal winds and appears to rise and fall in time with the Sun's 11-year
sunspot 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 variations in the number of observed sunspots on the Sun's surface. Ov ...
. The existence of lightning in the atmosphere of Venus has been controversial since the first suspected bursts were detected by the Soviet Venera probes. In 2006–07, ''
Venus Express ''Venus Express'' (VEX) was the first Venus exploration mission of the European Space Agency (ESA). Launched in November 2005, it arrived at Venus in April 2006 and began continuously sending back science data from its polar orbit around Venus. ...
'' clearly detected whistler mode waves, the signatures of lightning. Their intermittent appearance indicates a pattern associated with weather activity. According to these measurements, the lightning rate is at least half that on Earth, however other instruments have not detected lightning at all. The origin of any lightning remains unclear, but could originate from clouds or Venusian volcanoes. In 2007, ''Venus Express'' discovered that a huge double atmospheric polar vortex exists at the south pole. ''Venus Express'' discovered, in 2011, that an
ozone Ozone () (or trioxygen) is an Inorganic compound, inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , break ...
layer exists high in the atmosphere of Venus. In 2013
ESA The European Space Agency (ESA) is a 23-member international organization devoted to space exploration. With its headquarters in Paris and a staff of around 2,547 people globally as of 2023, ESA was founded in 1975 in the context of European ...
scientists reported that the
ionosphere The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays ...
of Venus streams outwards in a manner similar to "the ion tail seen streaming from a
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 ...
under similar conditions." In December 2015, and to a lesser extent in April and May 2016, researchers working on Japan's ''Akatsuki'' mission observed bow-shaped objects in the atmosphere of Venus. This was considered direct evidence of the existence of perhaps the largest stationary
gravity wave In fluid dynamics, gravity waves are waves in a fluid medium or at the interface between two media when the force of gravity or buoyancy tries to restore equilibrium. An example of such an interface is that between the atmosphere and the oc ...
s in the solar system. Colour and sound of the atmosphere at the surface have been recorded, with the sky having an orange-yellow colour, while at higher altitudes being white.


Orbit and rotation

Venus orbits the Sun at an average distance of about , and completes an orbit every 224.7 days. It completes 13 orbits in 7.998 years, so its position in our sky almost repeats every eight years. Although all planetary
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 ...
s are elliptical, Venus's orbit is currently the closest to circular, with an
eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-Centre (geometry), center, in geometry * Eccentricity (g ...
of less than 0.01. Simulations of the early solar system orbital dynamics have shown that the eccentricity of the Venus orbit may have been substantially larger in the past, reaching values as high as 0.31 and possibly impacting early climate evolution. Venus has
retrograde rotation Retrograde motion in astronomy is, in general, orbital or rotational motion of an object in the direction opposite the rotation of its primary, that is, the central object (right figure). It may also describe other motions such as precession or ...
, meaning that unlike most planets including Earth it rotates clockwise around its own axis, opposite to its
anticlockwise Two-dimensional rotation can occur in two possible directions or senses of rotation. Clockwise motion (abbreviated CW) proceeds in the same direction as a clock's hands relative to the observer: from the top to the right, then down and then to ...
rotation around the Sun. Therefore Venusian
sidereal day Sidereal time ("sidereal" pronounced ) is a system of timekeeping used especially by astronomers. Using sidereal time and the celestial coordinate system, it is easy to locate the positions of celestial objects in the night sky. Sidereal t ...
, 243 Earth days, lasts longer than a Venusian year, 224.7 Earth days. If Venus were
tidally locked Tidal locking between a pair of co-orbiting astronomical bodies occurs when one of the objects reaches a state where there is no longer any net change in its rotation rate over the course of a complete orbit. In the case where a tidally locked ...
to the Sun, it would always have the same face pointed to the Sun and its sidereal day would be 224.7 days. However, Venus's atmosphere is massive and it is close to the Sun, so differential heating of the atmosphere gives Venus a small retrograde rotation. The day length also fluctuates by up to 20 minutes for the same reason. Venus's rotation period measured with ''Magellan'' spacecraft data over a 500-day period is smaller than the rotation period measured during the 16-year period between the Magellan spacecraft and ''Venus Express'' visits, with a difference of about 6.5minutes. Because of the retrograde rotation, the length of a
solar day A synodic day (or synodic rotation period or solar day) is the period for a celestial object to rotate once in relation to the star it is orbiting, and is the basis of solar time. The synodic day is distinguished from the sidereal day, which is ...
on Venus is significantly shorter than the sidereal day, at 116.75 Earth days. One Venusian year is about 1.92Venusian solar days. To an observer on the surface of Venus, the Sun would rise in
the west West is a cardinal direction or compass point. West or The West may also refer to: Geography and locations Global context * The Western world * Western culture and Western civilization in general * The Western Bloc, countries allied with NAT ...
and set in the east, although Venus's opaque clouds prevent observing the Sun from the planet's surface. Venus may have formed from the
solar nebula There is evidence that the formation of the Solar System began about 4.6 bya, 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, whil ...
with a different rotation period and obliquity, reaching its current state because of chaotic spin changes caused by planetary perturbations and
tidal Tidal is the adjectival form of tide. Tidal may also refer to: * ''Tidal'' (album), a 1996 album by Fiona Apple * Tidal (king), a king involved in the Battle of the Vale of Siddim * TidalCycles, a live coding environment for music * Tidal (servic ...
effects on its dense atmosphere, a change that would have occurred over the course of billions of years. The rotation period of Venus may represent an equilibrium state between tidal locking to the Sun's gravitation, which tends to slow rotation, and an atmospheric tide created by solar heating of the thick Venusian atmosphere. The 584-day average interval between successive close approaches to Earth is almost exactly equal to 5Venusian solar days (5.001444 to be precise), but the hypothesis of a spin-orbit resonance with Earth has been discounted. Venus has no natural satellites. It has several
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 ...
s: the
quasi-satellite A quasi-satellite is an object in a specific type of co-orbital configuration (1:1 orbital resonance) with a planet (or dwarf planet) where the object stays close to that planet over many orbital periods. A quasi-satellite's orbit around the Sun ...
and two other temporary trojans, and . In the 17th century,
Giovanni Cassini Giovanni Domenico Cassini (8 June 1625 – 14 September 1712) was an Italian-French mathematician, astronomer, astrologer and engineer. Cassini was born in Perinaldo, near Imperia, at that time in the County of Nice, part of the Savoyard sta ...
reported a moon orbiting Venus, which was named
Neith Neith (, a borrowing of the Demotic (Egyptian), Demotic form , also spelled Nit, Net, or Neit) was an ancient Egyptian deity, possibly of Ancient Libya, Libyan origin. She was connected with warfare, as indicated by her emblem of two crossed b ...
and numerous sightings were reported over the following , but most were determined to be stars in the vicinity. Alex Alemi's and David Stevenson's 2006 study of models of the early Solar System at the
California Institute of Technology The California Institute of Technology (branded as Caltech) is a private research university in Pasadena, California, United States. The university is responsible for many modern scientific advancements and is among a small group of institutes ...
shows Venus likely had at least one moon created by a huge
impact event An impact event is a collision between astronomical objects causing measurable effects. Impact events have been found to regularly occur in planetary systems, though the most frequent involve asteroids, comets or meteoroids and have minimal effe ...
billions of years ago. About 10millionyears later, according to the study, another impact reversed the planet's spin direction and the resulting
tidal deceleration Tidal acceleration is an effect of the tidal forces between an orbiting natural satellite (e.g. the Moon) and the primary planet that it orbits (e.g. Earth). The acceleration causes a gradual recession of a satellite in a prograde orbit (satel ...
caused the Venusian moon gradually to spiral inward until it collided with Venus. If later impacts created moons, these were removed in the same way. An alternative explanation for the lack of satellites is the effect of strong solar tides, which can destabilize large satellites orbiting the inner terrestrial planets. The orbital space of Venus has a dust ring-cloud, with a suspected origin either from Venus–trailing asteroids, interplanetary dust migrating in waves, or the remains of the Solar System's original
circumstellar disc A Circumstellar disc (or circumstellar disk) is a torus, pancake or ring-shaped accretion disk of matter composed of gas, dust, planetesimals, asteroids, or collision fragments in orbit around a star. Around the youngest stars, they are the rese ...
that formed the
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 ...
.


Orbit in respect to Earth

Earth and Venus have a near
orbital resonance In celestial mechanics, orbital resonance occurs when orbiting bodies exert regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of small integers. Most commonly, this relation ...
of 13:8 (Earth orbits eight times for every 13 orbits of Venus). Therefore, they approach each other and reach
inferior conjunction In astronomy, a conjunction occurs when two astronomical objects or spacecraft appear to be close to each other in the sky. This means they have either the same right ascension or the same ecliptic longitude, usually as observed from Earth. When ...
in
synodic period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets, ...
s of 584 days, on average. The path that Venus makes in relation to Earth viewed geocentrically draws a
pentagram A pentagram (sometimes known as a pentalpha, pentangle, or star pentagon) is a regular five-pointed star polygon, formed from the diagonal line segments of a convex (or simple, or non-self-intersecting) regular pentagon. Drawing a circle around ...
over five synodic periods, shifting every period by 144°. This pentagram of Venus is sometimes referred to as the petals of Venus due to the path's visual similarity to a flower. When Venus lies between Earth and the Sun in inferior conjunction, it makes the closest approach to Earth of any planet at an average distance of . Because of the decreasing eccentricity of Earth's orbit, the minimum distances will become greater over tens of thousands of years. From the year1 to 5383, there are 526 approaches less than ; then, there are none for about 60,158 years. While Venus approaches Earth the closest, Mercury is more often the closest to Earth of all planets and to any other planet. Venus has the lowest
gravitational potential In classical mechanics, the gravitational potential is a scalar potential associating with each point in space the work (energy transferred) per unit mass that would be needed to move an object to that point from a fixed reference point in the ...
difference to Earth than any other planet, needing the lowest delta-v to transfer between them. Tidally Venus exerts the third strongest
tidal force The tidal force or tide-generating force is the difference in gravitational attraction between different points in a gravitational field, causing bodies to be pulled unevenly and as a result are being stretched towards the attraction. It is the ...
on Earth, after the Moon and the Sun, though significantly less.


Observability

To the
naked eye Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnification, magnifying, Optical telescope#Light-gathering power, light-collecting optical instrument, such as a telescope or microsc ...
, Venus appears as a white point of light brighter than any other planet or star (apart from the Sun). The planet's mean
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), ...
is −4.14 with a standard deviation of 0.31. The brightest magnitude occurs during the crescent phase about one month before or after an inferior conjunction. Venus fades to about magnitude −3 when it is backlit by the Sun, although the exact value depends on the phase angle. The planet is bright enough to be seen in broad daylight, but is more easily visible when the Sun is low on the horizon or setting. As an
inferior planet In the Solar System, a planet is said to be inferior or interior with respect to another planet if its orbit lies inside the other planet's orbit around the Sun. In this situation, the latter planet is said to be superior to the former. In the refe ...
, it always lies within about 47° of 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 ...
. Venus "overtakes" Earth every 584 days as it orbits the Sun. As it does so, it changes from the "Evening Star", visible after sunset, to the "Morning Star", visible before sunrise. Although Mercury, the other inferior planet, reaches a maximum elongation of only 28° and is often difficult to discern in twilight, Venus is hard to miss when it is at its brightest. Its greater maximum elongation means it is visible in dark skies long after sunset. As the brightest point-like object in the sky, Venus is a commonly misreported "
unidentified flying object An unidentified flying object (UFO) is an object or phenomenon seen in the sky but not yet identified or explained. The term was coined when United States Air Force (USAF) investigations into flying saucers found too broad a range of shapes ...
". Because Venus comes close to the earth at
inferior conjunction In astronomy, a conjunction occurs when two astronomical objects or spacecraft appear to be close to each other in the sky. This means they have either the same right ascension or the same ecliptic longitude, usually as observed from Earth. When ...
and has an orbit inclined to the plane of the earth's orbit, it can appear more than 8° north or south of the
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 ...
, more than any other planet or the moon. Every eight years around March it appears this far north of the ecliptic, in
Pisces Pisces may refer to: *Pisces (astrology), an astrological sign Astronomy *Pisces (constellation), a constellation ** Pisces Overdensity, an overdensity of stars in the Milky Way's halo that is situated in the Pisces constellation ** Pisces II, a ...
(such as in mid-March 2025), and every eight years it appears this far south of the ecliptic in August or September in
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, ...
(as in late August 2023). Venus can thus be north of the sun and appear as a morning star and an evening star on the same day, in the northern hemisphere. The timing of these north or south excursions gets slowly earlier in the year, and over 30 cycles (240 years) the cycle is gradually replaced by another cycle offset by three years, so the situation returns close to the original situation after 243 orbits of Earth, 395 of Venus.
Lunar occultations of Venus Lunar most commonly means "of or relating to the Moon". Lunar may also refer to: Arts and entertainment * ''Lunar'' (series), a series of video games * "Lunar" (song), by David Guetta * "Lunar", a song by Priestess from the 2009 album ''Prior t ...
, in which the moon blocks the view of Venus for observers in certain parts of the earth, occur on average about twice a year, sometimes several times in a year (though rarely).


Phases

As it orbits the Sun, Venus displays
phases Phase or phases may refer to: Science *State of matter, or phase, one of the distinct forms in which matter can exist *Phase (matter), a region of space throughout which all physical properties are essentially uniform *Phase space, a mathematica ...
like those of the
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 ...
in a
telescopic A telescope is an instrument designed for the observation of remote objects. Telescope(s) also may refer to: Music * The Telescopes, a British psychedelic band ** The Telescopes (album) * ''Telescope'' (album), by Circle, 2007 * ''The Telescope' ...
view. The planet appears as a small and "full" disc when it is on the opposite side of the Sun (at superior conjunction). Venus shows a larger disc and "quarter phase" at its maximum elongations from the Sun, and appears at its brightest in the night sky. The planet presents a much larger thin "crescent" in telescopic views as it passes along the near side between Earth and the Sun. Venus displays its largest size and "new phase" when it is between Earth and the Sun (at inferior conjunction). Its atmosphere is visible through telescopes by the halo of sunlight refracted around it. The phases are clearly visible in a 4" telescope. Although naked eye visibility of Venus's phases is disputed, records exist of observations of its crescent.


Daylight apparitions

When Venus is sufficiently bright with enough angular distance from the sun, it is easily observed in a clear daytime sky with the naked eye, though most people do not know to look for it. Astronomer
Edmund Halley Edmond (or Edmund) Halley (; – ) was an English astronomer, mathematician and physicist. He was the second Astronomer Royal in Britain, succeeding John Flamsteed in 1720. From an observatory he constructed on Saint Helena in 1676–77, H ...
calculated its maximum naked eye brightness in 1716, when many Londoners were alarmed by its appearance in the daytime. French emperor
Napoleon Bonaparte Napoleon Bonaparte (born Napoleone di Buonaparte; 15 August 1769 – 5 May 1821), later known by his regnal name Napoleon I, was a French general and statesman who rose to prominence during the French Revolution and led Military career ...
once witnessed a daytime apparition of the planet while at a reception in
Luxembourg Luxembourg, officially the Grand Duchy of Luxembourg, is a landlocked country in Western Europe. It is bordered by Belgium to the west and north, Germany to the east, and France on the south. Its capital and most populous city, Luxembour ...
. Another historical daytime observation of the planet took place during the inauguration of the American president
Abraham Lincoln Abraham Lincoln (February 12, 1809 – April 15, 1865) was the 16th president of the United States, serving from 1861 until Assassination of Abraham Lincoln, his assassination in 1865. He led the United States through the American Civil War ...
in Washington, D.C., on 4March 1865.


Transits

A
transit Transit may refer to: Arts and entertainment Film * ''Transit'' (1980 film), a 1980 Israeli film * ''Transit'' (1986 film), a Canadian short film * ''Transit'' (2005 film), a film produced by MTV and Staying-Alive about four people in countrie ...
of Venus is the appearance of Venus in front of the Sun, during
inferior conjunction In astronomy, a conjunction occurs when two astronomical objects or spacecraft appear to be close to each other in the sky. This means they have either the same right ascension or the same ecliptic longitude, usually as observed from Earth. When ...
. Since the orbit of Venus is slightly inclined relative to Earth's orbit, most inferior conjunctions with Earth, which occur every
synodic period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets, ...
of 1.6 years, do not produce a transit of Venus. Consequently, Venus transits only occur when an inferior conjunction takes place during some days of June or December, when the orbits of Venus and Earth cross a straight line with the Sun. This results in Venus transiting above Earth in a sequence currently of , , and , forming cycles of . Historically, transits of Venus were important, because they allowed astronomers to determine the size of the
astronomical unit The astronomical unit (symbol: au or AU) is a unit of length defined to be exactly equal to . Historically, the astronomical unit was conceived as the average Earth-Sun distance (the average of Earth's aphelion and perihelion), before its m ...
, and hence the size of the Solar System as shown by
Jeremiah Horrocks Jeremiah Horrocks (16183 January 1641), sometimes given as Jeremiah Horrox (the Latinised version that he used on the Emmanuel College register and in his Latin manuscripts), – See footnote 1 was an English astronomer. He was the first perso ...
in 1639 with the first known observation of a Venus transit (after history's first observed planetary transit in 1631, of Mercury). Only seven Venus transits have been observed so far, since their occurrences were calculated in the 1621 by
Johannes Kepler Johannes Kepler (27 December 1571 – 15 November 1630) was a German astronomer, mathematician, astrologer, Natural philosophy, natural philosopher and writer on music. He is a key figure in the 17th-century Scientific Revolution, best know ...
.
Captain Cook Captain James Cook (7 November 1728 – 14 February 1779) was a British Royal Navy officer, explorer, and cartographer famous for his three voyages of exploration to the Pacific and Southern Oceans, conducted between 1768 and 1779. He complet ...
sailed to
Tahiti Tahiti (; Tahitian language, Tahitian , ; ) is the largest island of the Windward Islands (Society Islands), Windward group of the Society Islands in French Polynesia, an overseas collectivity of France. It is located in the central part of t ...
in 1768 to record the third observed transit of Venus, which subsequently resulted in the exploration of the east coast of Australia. The latest pair was June 8, 2004 and June 5–6, 2012. The transit could be watched live from many online outlets or observed locally with the right equipment and conditions. The preceding pair of transits occurred in December 1874 and December 1882. The next transit will occur in December 2117 and December 2125.


Ashen light

A long-standing mystery of Venus observations is the so-called
ashen light Ashen light (also ''lumière cendrée'') is a hypothesised subtle glow that has been claimed to be seen on the night side of the planet Venus. The phenomenon has not been scientifically confirmed, and theories as to the observed phenomenon's cau ...
—an apparent weak illumination of its dark side, seen when the planet is in the crescent phase. The first claimed observation of ashen light was made in 1643, but the existence of the illumination has never been reliably confirmed. Observers have speculated it may result from electrical activity in the Venusian atmosphere, but it could be illusory, resulting from the physiological effect of observing a bright, crescent-shaped object. The ashen light has often been sighted when Venus is in the evening sky, when the evening terminator of the planet is towards Earth.


Observation and exploration history


Early observation

Venus is in Earth's sky bright enough to be visible without aid, making it one of the
classical planets A classical planet is an astronomical object that is visible to the naked eye and moves across the sky and its backdrop of fixed stars (the common stars which seem still in contrast to the planets), appearing as wandering stars. Visible to huma ...
that human cultures have known and identified throughout history, particularly for being the third brightest object in Earth's sky after the Sun and the Moon. Because the movements of Venus appear to be discontinuous (it disappears due to its proximity to the sun, for many days at a time, and then reappears on the other horizon), some cultures did not recognize Venus as a single entity; instead, they assumed it to be two separate stars on each horizon: the morning and evening star. Nonetheless, a
cylinder seal A cylinder seal is a small round cylinder, typically about one inch (2 to 3 cm) in width, engraved with written characters or figurative scenes or both, used in ancient times to roll an impression onto a two-dimensional surface, generally ...
from the
Jemdet Nasr period The Jemdet Nasr Period (also Jemdat Nasr period) is an archaeological culture in southern Mesopotamia (modern-day Iraq). It is generally dated from 3100 to 2900 BC. It is named after the type site Tell Jemdet Nasr, where the assemblage typical fo ...
and the
Venus tablet of Ammisaduqa The Venus tablet of Ammisaduqa (''Enuma Anu Enlil'' Tablet 63) is the record of astronomical positions for Venus, as preserved in numerous cuneiform clay tablet, tablets dating from the first millennium BC. Scholars believe that this astronomical ...
from the
First Babylonian dynasty The Old Babylonian Empire, or First Babylonian Empire, is dated to , and comes after the end of Sumerian power with the destruction of the Third Dynasty of Ur, and the subsequent Isin-Larsa period. The Chronology of the Ancient Near East, chrono ...
indicate that the ancient Sumerians already knew that the morning and evening stars were the same celestial object. In the Old
Babylonia Babylonia (; , ) was an Ancient history, ancient Akkadian language, Akkadian-speaking state and cultural area based in the city of Babylon in central-southern Mesopotamia (present-day Iraq and parts of Kuwait, Syria and Iran). It emerged as a ...
n period, the planet Venus was known as Ninsi'anna, and later as Dilbat. The name "Ninsi'anna" translates to "divine lady, illumination of heaven", which refers to Venus as the brightest visible "star". Earlier spellings of the name were written with the
cuneiform Cuneiform is a Logogram, logo-Syllabary, syllabic writing system that was used to write several languages of the Ancient Near East. The script was in active use from the early Bronze Age until the beginning of the Common Era. Cuneiform script ...
sign si4 (= SU, meaning "to be red"), and the original meaning may have been "divine lady of the redness of heaven", in reference to the colour of the morning and evening sky. The Chinese historically referred to the morning Venus as "the Great White" ( ) or "the Opener (Starter) of Brightness" ( ), and the evening Venus as "the Excellent West One" ( ). The ancient Greeks initially believed Venus to be two separate stars:
Phosphorus Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...
, the morning star, and
Hesperus In Greek mythology, Hesperus (; ) is the Evening Star, the planet Venus in the evening. A son of the dawn goddess Eos ( Roman Aurora), he is the half-brother of her other son, Phosphorus (also called Eosphorus; the "Morning Star"). Hesperus' Rom ...
, the evening star.
Pliny the Elder Gaius Plinius Secundus (AD 23/24 79), known in English as Pliny the Elder ( ), was a Roman Empire, Roman author, Natural history, naturalist, and naval and army commander of the early Roman Empire, and a friend of the Roman emperor, emperor Vesp ...
credited the realization that they were a single object to
Pythagoras Pythagoras of Samos (;  BC) was an ancient Ionian Greek philosopher, polymath, and the eponymous founder of Pythagoreanism. His political and religious teachings were well known in Magna Graecia and influenced the philosophies of P ...
in the sixth century BC, while
Diogenes Laërtius Diogenes Laërtius ( ; , ; ) was a biographer of the Greek philosophers. Little is definitively known about his life, but his surviving book ''Lives and Opinions of Eminent Philosophers'' is a principal source for the history of ancient Greek ph ...
argued that
Parmenides Parmenides of Elea (; ; fl. late sixth or early fifth century BC) was a Pre-Socratic philosophy, pre-Socratic ancient Greece, Greek philosopher from Velia, Elea in Magna Graecia (Southern Italy). Parmenides was born in the Greek colony of Veli ...
(early fifth century) was probably responsible for this discovery. Though they recognized Venus as a single object, the ancient Romans continued to designate the morning aspect of Venus as
Lucifer The most common meaning for Lucifer in English is as a name for the Devil in Christian theology. He appeared in the King James Version of the Bible in Isaiah and before that in the Vulgate (the late-4th-century Latin translation of the Bib ...
, literally "Light-Bringer", and the evening aspect as Vesper, both of which are literal translations of their traditional Greek names. In the second century, in his astronomical treatise ''
Almagest The ''Almagest'' ( ) is a 2nd-century Greek mathematics, mathematical and Greek astronomy, astronomical treatise on the apparent motions of the stars and planetary paths, written by Ptolemy, Claudius Ptolemy ( ) in Koine Greek. One of the most i ...
'',
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 ...
theorized that both Mercury and Venus were located between the Sun and the Earth. The 11th-century
Persian Persian may refer to: * People and things from Iran, historically called ''Persia'' in the English language ** Persians, the majority ethnic group in Iran, not to be conflated with the Iranic peoples ** Persian language, an Iranian language of the ...
astronomer
Avicenna Ibn Sina ( – 22 June 1037), commonly known in the West as Avicenna ( ), was a preeminent philosopher and physician of the Muslim world, flourishing during the Islamic Golden Age, serving in the courts of various Iranian peoples, Iranian ...
claimed to have observed a
transit of Venus A transit of Venus takes place when Venus passes directly between the Sun and the Earth (or any other superior planet), becoming visible against (and hence obscuring a small portion of) the solar disk. During a transit, Venus is visible as ...
(although there is some doubt about it), which later astronomers took as confirmation of Ptolemy's theory. In the 12th century, the Andalusian astronomer
Ibn Bajjah Abū Bakr Muḥammad ibn Yaḥyà ibn aṣ-Ṣā’igh at-Tūjībī ibn Bājja (), known simply as Ibn Bajja () or his Latinized name Avempace (;  – 1138), was an Arab polymath, whose writings include works regarding astronomy, physi ...
observed "two planets as black spots on the face of the Sun"; these were thought to be the transits of Venus and Mercury by 13th-century
Maragha Maragheh () is a city in the Central District of Maragheh County, East Azerbaijan province, Iran, serving as capital of both the county and the district. Maragheh is on the bank of the river Sufi Chay. It is from Tabriz, the largest city ...
astronomer Qotb al-Din Shirazi, though this cannot be true as there were no Venus transits in Ibn Bajjah's lifetime.


Venus and early modern astronomy

When the planet was first observed with a telescope in December 1610, by the Italian physicist
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 ...
, he found it showed
phases Phase or phases may refer to: Science *State of matter, or phase, one of the distinct forms in which matter can exist *Phase (matter), a region of space throughout which all physical properties are essentially uniform *Phase space, a mathematica ...
like the Moon, varying from crescent to gibbous to full and vice versa. When Venus is furthest from the Sun in the sky, it shows a half-lit phase, and when it is closest to the Sun in the sky, it shows as a crescent or full phase. This could be possible only if Venus orbited the Sun, reported by Galileo in his 1613
Letters on Sunspots '' Letters on Sunspots'' (''Istoria e Dimostrazioni intorno alle Macchie Solari'') was a pamphlet written by Galileo Galilei in 1612 and published in Rome by the Accademia dei Lincei in 1613. In it, Galileo outlined his recent observation of dark ...
, becoming one of the first observations to clearly contradict the Ptolemaic
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 ...
that the Solar System was concentric and centred on Earth. The 1631
transit of Venus A transit of Venus takes place when Venus passes directly between the Sun and the Earth (or any other superior planet), becoming visible against (and hence obscuring a small portion of) the solar disk. During a transit, Venus is visible as ...
, while not recorded, was the first one successfully predicted, by
Johannes Kepler Johannes Kepler (27 December 1571 – 15 November 1630) was a German astronomer, mathematician, astrologer, Natural philosophy, natural philosopher and writer on music. He is a key figure in the 17th-century Scientific Revolution, best know ...
and his calculations, which he published in 1629. The following 1639 transit of Venus was accurately predicted by
Jeremiah Horrocks Jeremiah Horrocks (16183 January 1641), sometimes given as Jeremiah Horrox (the Latinised version that he used on the Emmanuel College register and in his Latin manuscripts), – See footnote 1 was an English astronomer. He was the first perso ...
and observed by him and his friend,
William Crabtree William Crabtree (1610 – 1644) was an English astronomer, mathematician, and merchant from Broughton, then in the Hundred of Salford, Lancashire, England. He was one of only two people to observe and record the first predicted transit of ...
, at each of their respective homes, on 4December 1639 (24 November under the
Julian calendar The Julian calendar is a solar calendar of 365 days in every year with an additional leap day every fourth year (without exception). The Julian calendar is still used as a religious calendar in parts of the Eastern Orthodox Church and in parts ...
in use at that time). The
atmosphere of Venus The atmosphere of Venus is the very dense layer of gases surrounding the planet Venus. Venus's atmosphere is composed of 96.5% carbon dioxide and 3.5% nitrogen, with other chemical compounds present only in trace amounts. It is much denser and ho ...
was discovered in 1761 by Russian polymath
Mikhail Lomonosov Mikhail Vasilyevich Lomonosov (; , ; – ) was a Russian polymath, scientist and writer, who made important contributions to literature, education, and science. Among his discoveries were the atmosphere of Venus and the law of conservation of ...
. Venus's atmosphere was observed in 1790 by German astronomer
Johann Schröter Johann, typically a male given name, is the German form of ''Iohannes'', which is the Latin form of the Greek name ''Iōánnēs'' (), itself derived from Hebrew name '' Yochanan'' () in turn from its extended form (), meaning "Yahweh is Gracious ...
. Schröter found when the planet was a thin crescent, the cusps extended through more than 180°. He correctly surmised this was due to
scattering In physics, scattering is a wide range of physical processes where moving particles or radiation of some form, such as light or sound, are forced to deviate from a straight trajectory by localized non-uniformities (including particles and radiat ...
of sunlight in a dense atmosphere. Later, American astronomer Chester Smith Lyman observed a complete ring around the dark side of the planet when it was at
inferior conjunction In astronomy, a conjunction occurs when two astronomical objects or spacecraft appear to be close to each other in the sky. This means they have either the same right ascension or the same ecliptic longitude, usually as observed from Earth. When ...
, providing further evidence for an atmosphere. The atmosphere complicated efforts to determine a rotation period for the planet, and observers such as Italian-born astronomer
Giovanni Cassini Giovanni Domenico Cassini (8 June 1625 – 14 September 1712) was an Italian-French mathematician, astronomer, astrologer and engineer. Cassini was born in Perinaldo, near Imperia, at that time in the County of Nice, part of the Savoyard sta ...
and Schröter incorrectly estimated periods of about from the motions of markings on the planet's apparent surface.


Early 20th century advances

Little more was discovered about Venus until the 20th century. Its almost featureless disc gave no hint what its surface might be like, and it was only with the development of
spectroscopic 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. Spectrosc ...
and
ultraviolet Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of ...
observations that more of its secrets were revealed. Spectroscopic observations in the 1900s gave the first clues about the Venusian rotation.
Vesto Slipher Vesto Melvin Slipher (; November 11, 1875 – November 8, 1969) was an American astronomer who performed the first measurements of radial velocities for galaxies. He was the first to discover that distant galaxies are redshifted, thus providing ...
tried to measure the
Doppler shift 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 t ...
of light from Venus, but found he could not detect any rotation. He surmised the planet must have a much longer
rotation period In astronomy, the rotation period or spin period of a celestial object (e.g., star, planet, moon, asteroid) has two definitions. The first one corresponds to the '' sidereal rotation period'' (or ''sidereal day''), i.e., the time that the objec ...
than had previously been thought. The first ultraviolet observations were carried out in the 1920s, when Frank E. Ross found that ultraviolet photographs revealed considerable detail that was absent in visible and
infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...
radiation. He suggested this was due to a dense, yellow lower atmosphere with high
cirrus cloud Cirrus ( cloud classification symbol: Ci) is a genus of high cloud made of ice crystals. Cirrus clouds typically appear delicate and wispy with white strands. In the Earth's atmosphere, cirrus are usually formed when warm, dry air rises, causing ...
s above it. It had been noted that Venus had no discernible
oblateness Flattening is a measure of the compression of a circle or sphere along a diameter to form an ellipse or an ellipsoid of revolution (spheroid) respectively. Other terms used are ellipticity, or oblateness. The usual notation for flattening is f ...
in its disk, suggesting a slow rotation, and some astronomers concluded based on this that it was
tidally locked Tidal locking between a pair of co-orbiting astronomical bodies occurs when one of the objects reaches a state where there is no longer any net change in its rotation rate over the course of a complete orbit. In the case where a tidally locked ...
like Mercury was believed to be at the time; but other researchers had detected a significant quantity of heat coming from the planet's nightside, suggesting a quick rotation (a high surface temperature was not suspected at the time), confusing the issue. Later work in the 1950s showed the rotation was retrograde.


Space age

The first
interplanetary spaceflight Interplanetary spaceflight or interplanetary travel is spaceflight (Human spaceflight, crewed or Uncrewed spacecraft, uncrewed) between bodies within a single planetary system. Spaceflights become interplanetary by accelerating spacecrafts beyond ...
attempt was in 1961 when the robotic space probe ''
Venera 1 ''Venera 1'' ( meaning ''Venus 1''), also known as Venera-1VA No.2 and occasionally in the West as ''Sputnik 8'', was the first spacecraft to perform an interplanetary flight and the first to fly past Venus, as part of the Soviet Union's Venera ...
'' of the Soviet
Venera The Venera (, 'Venus') program was a series of space probes developed by the Soviet Union between 1961 and 1984 to gather information about the planet Venus. Thirteen probes successfully entered the Venusian atmosphere, including the two ...
programme flew to Venus. It lost contact en route. The first successful interplanetary mission, also to Venus, was ''
Mariner 2 Mariner 2 (Mariner-Venus 1962), an American space probe to Venus, was the first robotic space probe to report successfully from a planetary encounter. The first successful spacecraft in the NASA Mariner program, it was a simplified version of t ...
'' of the United States'
Mariner program The Mariner program was conducted by the American space agency NASA to explore other planets. Between 1962 and late 1973, NASA's Jet Propulsion Laboratory (JPL) designed and built 10 robotic interplanetary probes named Mariner to explore the in ...
me, passing on 14 December 1962 at above the surface of Venus and gathering data on the planet's atmosphere. Additionally radar observations of Venus were first carried out in the 1960s, and provided the first measurements of the rotation period, which were close to the actual value. ''
Venera 3 Venera 3 ( meaning ''Venus 3'') was a Venera program space probe that was built and launched by the Soviet Union to explore the surface of Venus. It was launched on 16 November 1965 at 04:19 UTC from Baikonur, Kazakhstan, USSR. The probe comp ...
'', launched in 1966, became humanity's first probe and lander to reach and impact another celestial body other than the Moon, but could not return data as it crashed into the surface of Venus. In 1967, ''
Venera 4 Venera 4 (), also designated 4V-1 No.310, was a probe in the Soviet Venera program for the exploration of Venus. The probe comprised a lander, designed to enter the Venusian atmosphere and parachute to the surface, and a carrier/ flyby space ...
'' was launched and successfully deployed science experiments in the Venusian atmosphere before impacting. ''Venera 4'' showed the surface temperature was hotter than ''Mariner 2'' had calculated, at almost , determined that the atmosphere was 95% carbon dioxide (), and discovered that Venus's atmosphere was considerably denser than ''Venera 4'' designers had anticipated. In an early example of space cooperation the data of ''Venera 4'' was joined with the 1967 ''
Mariner 5 Mariner 5 (Mariner V or Mariner Venus 1967) was a spacecraft of the Mariner program that carried a complement of experiments to probe Venus' atmosphere by radio occultation, measure the hydrogen Lyman-alpha (hard ultraviolet) spectrum, and sam ...
'' data, analysed by a combined Soviet–American science team in a series of colloquia over the following year. On 15 December 1970, ''
Venera 7 Venera 7 () was a Soviet spacecraft, part of the Venera series of probes to Venus. When it landed on the Venusian surface on 15 December 1970, it became the first spacecraft to soft land on another planet and the first to transmit data from the ...
'' became the first spacecraft to soft land on another planet and the first to transmit data from there back to Earth. In 1974, ''
Mariner 10 ''Mariner 10'' was an American Robotic spacecraft, robotic space probe launched by NASA on 3 November 1973, to fly by the planets Mercury (planet), Mercury and Venus. It was the first spacecraft to perform flybys of multiple planets. ''Marin ...
'' swung by Venus to bend its path towards Mercury and took ultraviolet photographs of the clouds, revealing the extraordinarily high wind speeds in the Venusian atmosphere. This was the first interplanetary
gravity assist A gravity assist, gravity assist maneuver, swing-by, or generally a gravitational slingshot in orbital mechanics, is a type of spaceflight flyby (spaceflight), flyby which makes use of the relative movement (e.g. orbit around the Sun) and gra ...
ever used, a technique which would be used by later probes. Radar observations in the 1970s revealed details of the Venusian surface for the first time. Pulses of radio waves were beamed at the planet using the radio telescope at
Arecibo Observatory The Arecibo Observatory, also known as the National Astronomy and Ionosphere Center (NAIC) and formerly known as the Arecibo Ionosphere Observatory, is an observatory in Barrio Esperanza, Arecibo, Puerto Rico owned by the US National Science F ...
, and the echoes revealed two highly reflective regions, designated the
Alpha Alpha (uppercase , lowercase ) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter ''aleph'' , whose name comes from the West Semitic word for ' ...
and
Beta Beta (, ; uppercase , lowercase , or cursive ; or ) is the second letter of the Greek alphabet. In the system of Greek numerals, it has a value of 2. In Ancient Greek, beta represented the voiced bilabial plosive . In Modern Greek, it represe ...
regions. The observations revealed a bright region attributed to mountains, which was called
Maxwell Montes Maxwell Montes is a mountain range on the planet Venus, of which Skadi Mons is the List of tallest mountains in the Solar System, highest. General description Located on Ishtar Terra, the more northern of the planet's two major highlands, Ma ...
. These three features are now the only ones on Venus that do not have female names. In 1975, the Soviet ''
Venera 9 Venera 9 (), manufacturer's designation: 4V-1 No. 660, was a Soviet uncrewed space mission to Venus. It consisted of an orbiter and a lander. It was launched on June 8, 1975, at 02:38:00 UTC and had a mass of . The orbiter was the first sp ...
'' and '' 10'' landers transmitted the first images from the surface of Venus, which were in black and white. NASA obtained additional data with the
Pioneer Venus project The Pioneer Venus project was part of the Pioneer program consisting of two spacecraft, the Pioneer Venus Orbiter and the Pioneer Venus Multiprobe, launched to Venus in 1978. The program was managed by NASA's Ames Research Center. The Pionee ...
, consisting of two separate missions: the
Pioneer Venus Multiprobe The Pioneer Venus Multiprobe, also known as Pioneer Venus 2 or Pioneer 13, was a spacecraft launched in 1978 to explore Venus as part of NASA's Pioneer program. This part of the mission included a Satellite bus, spacecraft bus which was launched ...
and
Pioneer Venus Orbiter The ''Pioneer Venus Orbiter'', also known as ''Pioneer Venus 1'' or ''Pioneer 12'', was a mission to Venus conducted by NASA as part of the Pioneer Venus project. Launched in May 1978 atop an Atlas-Centaur rocket, the spacecraft was inserted into ...
, orbiting Venus between 1978 and 1992. In 1982 the first monochrome colour filters images of the surface were obtained with the Soviet '' Venera 13'' and '' 14'' landers. After ''
Venera 15 Venera 15 ( meaning ''Venus 15'') was a spacecraft sent to Venus by the Soviet Union. This uncrewed orbiter was to map the surface of Venus using high resolution imaging systems. The spacecraft was identical to Venera 16 and based on modificat ...
'' and '' 16'' operated between 1983 and 1984 in orbit, conducting detailed mapping of 25% of Venus's terrain (from the north pole to 30°N latitude), the Soviet Venera programme came to a close. In 1985 the Soviet
Vega programme Vega is the brightest star in the northern constellation of Lyra. It has the Bayer designation α Lyrae, which is Latinised to Alpha Lyrae and abbreviated Alpha Lyr or α Lyr. This star is relatively close at only from the Sun, and ...
with its ''
Vega 1 Vega 1 (along with its twin Vega 2) was a Soviet space probe, part of the Vega program. The spacecraft was a development of the earlier ''Venera'' craft. They were designed by Babakin Space Centre and constructed as 5VK by Lavochkin at Khim ...
'' and ''
Vega 2 Vega 2 (along with Vega 1) was a Soviet space probe part of the Vega program to explore Halley's comet and Venus. The spacecraft was a development of the earlier '' Venera'' craft. The name VeGa (ВеГа) combines the first two letters of the R ...
'' missions carried the last entry probes and carried the first ever extraterrestrial
aerobot An aerobot is an aerial robot, usually used in the context of an uncrewed space probe or unmanned aerial vehicle. While work has been done since the 1960s on robot " rovers" to explore the Moon and other worlds in the Solar System, such machines ...
s for the first time achieving atmospheric flight outside Earth by employing inflatable balloons. Between 1990 and 1994, ''
Magellan Ferdinand Magellan ( – 27 April 1521) was a Portuguese people, Portuguese explorer best known for having planned and led the Magellan expedition, 1519–22 Spanish expedition to the East Indies. During this expedition, he also discovered t ...
'' operated in orbit until deorbiting, mapping the surface of Venus. Furthermore, probes like ''
Galileo 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 ...
'' (1990), ''
Cassini–Huygens ''Cassini–Huygens'' ( ), commonly called ''Cassini'', was a space research, space-research mission by NASA, the European Space Agency (ESA), and the Italian Space Agency (ASI) to send a space probe to study the planet Saturn and its system, i ...
'' (1998/1999), and ''
MESSENGER Messenger, Messengers, The Messenger or The Messengers may refer to: People * Courier, a person or company that delivers messages, packages, or mail * Messenger (surname) * Bicycle messenger, a bicyclist who transports packages through cities * M ...
'' (2006/2007) visited Venus with flybys en route to other destinations. In April 2006, ''
Venus Express ''Venus Express'' (VEX) was the first Venus exploration mission of the European Space Agency (ESA). Launched in November 2005, it arrived at Venus in April 2006 and began continuously sending back science data from its polar orbit around Venus. ...
'', the first dedicated Venus mission by the
European Space Agency The European Space Agency (ESA) is a 23-member International organization, international organization devoted to space exploration. With its headquarters in Paris and a staff of around 2,547 people globally as of 2023, ESA was founded in 1975 ...
(ESA), entered orbit around Venus. ''Venus Express'' provided unprecedented observation of Venus's atmosphere. ESA concluded the ''Venus Express'' mission in December 2014 deorbiting it in January 2015. In 2010, the first successful interplanetary
solar sail Solar sails (also known as lightsails, light sails, and photon sails) are a method of spacecraft propulsion using radiation pressure exerted by sunlight on large surfaces. A number of spaceflight missions to test solar propulsion and navigati ...
spacecraft
IKAROS IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) is a Japan Aerospace Exploration Agency (JAXA) experimental spacecraft. The spacecraft was launched on 20 May 2010, aboard an H-IIA rocket, together with the ''Akatsuki'' (V ...
travelled to Venus for a flyby. Between 2015 and 2024 Japan's ''
Akatsuki may refer to: Places * Akatsuki Gakuenmae Station, is a passenger railway station located in the city of Yokkaichi People *, Japanese author in the I Novel genre *, Japanese manga artist *, Japanese light novel author and manga writer Ships * ...
'' probe was active in orbit around Venus and
BepiColombo BepiColombo is a joint mission of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) to the planet Mercury. The mission comprises two satellites launched together: the Mercury Planetary Orbiter (MPO) and ''Mio'' ...
performed flybys in 2020/2021.


Active and planned missions

there are no active probes at Venus, with
Parker Solar Probe The Parker Solar Probe (PSP; previously Solar Probe, Solar Probe Plus or Solar Probe+) is a NASA space probe launched in 2018 to make observations of the Stellar corona, Sun's outer corona. It used repeated Gravity assist, gravity assists from ...
scheduled to return repeatedly to Venus until 2030. Several probes are under development as well as multiple proposed missions still in their early conceptual stages. The next Venus mission scheduled is the
Venus Life Finder Venus Life Finder is a planned Venus space probe designed to detect Life on Venus, signs of life in the Atmosphere of Venus, Venusian atmosphere. Slated to be the first Private spaceflight, private mission to another planet, the spacecraft is b ...
, expected to launch not earlier than summer 2026. Indian ISRO is working on
Venus Orbiter Mission The Venus Orbiter Mission (VOM), unofficially known as ''Shukrayaan'' (Sanskrit: 'Venus', 'Craft, Vehicle'), is a planned Indian Space Research Organisation (ISRO) mission to study the surface and atmosphere of Venus. Funds were released ...
, aiming to launch it in 2028. UAE mission to asteroids,
MBR Explorer The MBR Explorer is a planned UAESA space probe designed to journey to seven different main belt asteroids. Proposed under the Emirates Mission to the Asteroid Belt, it is named in recognition of the foundational role driving the creation and gr ...
, will perform a flyby of the planet. NASA approved two missions to the planet,
VERITAS In Roman mythology, Veritas (), meaning Truth, is the Goddess of Truth, a daughter of Saturn (mythology), Saturn (called Cronus by the Greeks, the Titan (mythology), Titan of Time, perhaps first by Plutarch) and the mother of Virtus (deity), Vi ...
and
DAVINCI Leonardo di ser Piero da Vinci (15 April 1452 - 2 May 1519) was an Italian polymath of the High Renaissance who was active as a painter, draughtsman, engineer, scientist, theorist, sculptor, and architect. While his fame initially rested o ...
, planned to be launched not earlier then 2031. ESA plans to launch
EnVision Envision may refer to: Organizations * Envision EMI, a management company based in Virginia, USA * Envision Energy, a wind turbine manufacturer and energy technology company based in Shanghai, China * Envision Financial, a financial institution ...
also in 2031.


Objectives

Venus has been identified for future research as an important case for understanding: * the origins of the solar system and Earth, and if systems and planets like ours are common or rare in the universe. * how planetary bodies evolve from their primordial states to today's diverse objects. * the development of conditions leading to habitable environments and life.


Crewed mission concepts

Venus has been considered since the 1960s as a waypoint for
crewed missions to Mars The idea of sending humans to Mars has been the subject of aerospace engineering and scientific studies since the late 1940s as part of the broader exploration of Mars. Long-term proposals have included Colonization of Mars, sending settlers an ...
through
opposition Opposition may refer to: Arts and media * ''Opposition'' (Altars EP), 2011 EP by Christian metalcore band Altars * The Opposition (band), a London post-punk band * ''The Opposition with Jordan Klepper'', a late-night television series on Comedy ...
missions instead of direct conjunction missions with Venus
gravity assist A gravity assist, gravity assist maneuver, swing-by, or generally a gravitational slingshot in orbital mechanics, is a type of spaceflight flyby (spaceflight), flyby which makes use of the relative movement (e.g. orbit around the Sun) and gra ...
flybys, demonstrating that they should be quicker and safer missions to
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 ...
, with better return or abort flight windows, and less or the same amount of radiation exposure from the flight as direct Mars flights.


Possible atmospheric habitation

While the surface conditions of Venus are extremely hostile, the atmospheric pressure, temperature, and solar and cosmic radiation 50 km above the surface are similar to those at Earth's surface ("clement conditions"). Among the many engineering challenges for any human presence in the atmosphere of Venus are the corrosive amounts of
sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen, ...
in the atmosphere.
Aerostat An aerostat (, via French) or lighter-than-air aircraft is an aircraft that relies on buoyancy to maintain flight. Aerostats include unpowered balloons (free-flying or tethered) and powered airships. The relative density of an aerostat as a ...
s for crewed exploration and possibly for permanent " floating cities" in the Venusian atmosphere have been proposed as an alternative to the popular idea of living on
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 such as
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 ...
. NASA's
High Altitude Venus Operational Concept High Altitude Venus Operational Concept (HAVOC) was a proposed set of crewed NASA mission concepts to the planet Venus. All human portions of the missions would be conducted from lighter-than-air craft or from orbit. A similar concept, the "Floa ...
was a training concept to study a crewed aerostat design.


Search for life

Speculation on the possibility of life on Venus's surface decreased significantly after the early 1960s when it became clear that conditions were extreme compared to those on Earth. Venus's extreme temperatures and atmospheric pressure make water-based life, as currently known, unlikely. Some scientists have speculated that thermoacidophilic
extremophile An extremophile () is an organism that is able to live (or in some cases thrive) in extreme environments, i.e., environments with conditions approaching or stretching the limits of what known life can adapt to, such as extreme temperature, press ...
microorganism A microorganism, or microbe, is an organism of microscopic scale, microscopic size, which may exist in its unicellular organism, single-celled form or as a Colony (biology)#Microbial colonies, colony of cells. The possible existence of unseen ...
s might exist in the cooler, acidic upper layers of the Venusian
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 ...
. Such speculations go back to 1967, when
Carl Sagan Carl Edward Sagan (; ; November 9, 1934December 20, 1996) was an American astronomer, planetary scientist and science communicator. His best known scientific contribution is his research on the possibility of extraterrestrial life, including e ...
and
Harold J. Morowitz Harold Joseph Morowitz (December 4, 1927 – March 22, 2016) was an American biophysicist who studied the application of thermodynamics to living systems. Author of numerous books and articles, his work includes technical monographs as well as ess ...
suggested in a ''
Nature Nature is an inherent character or constitution, particularly of the Ecosphere (planetary), ecosphere or the universe as a whole. In this general sense nature refers to the Scientific law, laws, elements and phenomenon, phenomena of the physic ...
'' article that tiny objects detected in Venus's clouds might be organisms similar to Earth's bacteria (which are of approximately the same size): :While the surface conditions of Venus make the hypothesis of life there implausible, the clouds of Venus are a different story altogether. As was pointed out some years ago, water,
carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
and sunlight—the prerequisites for
photosynthesis Photosynthesis ( ) is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabo ...
—are plentiful in the vicinity of the clouds. In August 2019, astronomers led by Yeon Joo Lee reported that long-term pattern of absorbance and
albedo Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...
changes in the atmosphere of the planet Venus caused by "unknown absorbers", which may be chemicals or even large colonies of microorganisms high up in the atmosphere of the planet, affect the climate. Their light absorbance is almost identical to that of micro-organisms in Earth's clouds. Similar conclusions have been reached by other studies. In September 2020, a team of astronomers led by Jane Greaves from
Cardiff University Cardiff University () is a public research university in Cardiff, Wales. It was established in 1883 as the University College of South Wales and Monmouthshire and became a founding college of the University of Wales in 1893. It was renamed Unive ...
announced the likely detection of
phosphine Phosphine (IUPAC name: phosphane) is a colorless, flammable, highly toxic compound with the chemical formula , classed as a pnictogen hydride. Pure phosphine is odorless, but technical grade samples have a highly unpleasant odor like rotting ...
, a gas not known to be produced by any known chemical processes on the Venusian surface or atmosphere, in the upper levels of the planet's clouds. One proposed source for this phosphine is living organisms. The phosphine was detected at heights of at least above the surface, and primarily at mid-latitudes with none detected at the poles. The discovery prompted
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 ...
administrator
Jim Bridenstine James Frederick Bridenstine (born June 15, 1975) is an American military officer and politician who served as the 13th administrator of the National Aeronautics and Space Administration (NASA). Bridenstine was the United States representative ...
to publicly call for a new focus on the study of Venus, describing the phosphine find as "the most significant development yet in building the case for life off Earth". Subsequent analysis of the data-processing used to identify phosphine in the atmosphere of Venus has raised concerns that the detection-line may be an artefact. The use of a 12th-order polynomial fit may have amplified noise and generated a false reading (see
Runge's phenomenon In the mathematical field of numerical analysis, Runge's phenomenon () is a problem of oscillation at the edges of an interval that occurs when using polynomial interpolation with polynomials of high degree over a set of equispaced interpolation ...
). Observations of the atmosphere of Venus at other parts of the electromagnetic spectrum in which a phosphine absorption line would be expected did not detect phosphine. By late October 2020, re-analysis of data with a proper subtraction of background did not show a
statistically significant In statistical hypothesis testing, a result has statistical significance when a result at least as "extreme" would be very infrequent if the null hypothesis were true. More precisely, a study's defined significance level, denoted by \alpha, is the ...
detection of phosphine. Members of the team around Greaves, are working as part of a project by the
MIT The Massachusetts Institute of Technology (MIT) is a private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of modern technology and sc ...
to send with the rocket company
Rocket Lab Rocket Lab Corporation is a Public company, publicly traded aerospace manufacturer and List of launch service providers, launch service provider. Its Rocket Lab Electron, Electron orbital rocket launches Small satellite, small satellites, and ha ...
the first private interplanetary space craft, to look for organics by entering the atmosphere of Venus with a probe named
Venus Life Finder Venus Life Finder is a planned Venus space probe designed to detect Life on Venus, signs of life in the Atmosphere of Venus, Venusian atmosphere. Slated to be the first Private spaceflight, private mission to another planet, the spacecraft is b ...
.


Planetary protection

The
Committee on Space Research The Committee on Space Research (COSPAR) was established on October 3, 1958 by the International Council for Scientific Unions (ICSU) and its first chair was Hildegard Korf Kallmann-Bijl. Among COSPAR's objectives are the promotion of scienti ...
is a scientific organization established by the
International Council for Science The International Council for Science (ICSU, after its former name, International Council of Scientific Unions) was an international non-governmental organization devoted to international cooperation in the advancement of science. Its members ...
. Among their responsibilities is the development of recommendations for avoiding
interplanetary contamination Interplanetary contamination refers to biological contamination of a planetary body by a space probe or spacecraft, either deliberate or unintentional. There are two types of interplanetary contamination: *''Forward contamination'' is the transf ...
. For this purpose, space missions are categorized into five groups. Due to the harsh surface environment of Venus, Venus has been under the
planetary protection Planetary protection is a guiding principle in the design of an interplanetary mission, aiming to prevent biological contamination of both the target celestial body and the Earth in the case of sample-return missions. Planetary protection refle ...
category two. This indicates that there is only a remote chance that spacecraft-borne contamination could compromise investigations.


In culture

Venus is among the most prominent features in the night sky, and has been treated as particularly important in
mythology Myth is a genre of folklore consisting primarily of narratives that play a fundamental role in a society. For scholars, this is very different from the vernacular usage of the term "myth" that refers to a belief that is not true. Instead, the ...
,
astrology Astrology is a range of Divination, divinatory practices, recognized as pseudoscientific since the 18th century, that propose that information about human affairs and terrestrial events may be discerned by studying the apparent positions ...
and
fiction Fiction is any creative work, chiefly any narrative work, portraying character (arts), individuals, events, or setting (narrative), places that are imagination, imaginary or in ways that are imaginary. Fictional portrayals are thus inconsistent ...
across many different cultures. Several hymns praise
Inanna Inanna is the List of Mesopotamian deities, ancient Mesopotamian goddess of war, love, and fertility. She is also associated with political power, divine law, sensuality, and procreation. Originally worshipped in Sumer, she was known by the Akk ...
in her role as the goddess of the planet Venus. Theology professor Jeffrey Cooley has argued that, in many myths, Inanna's movements may correspond with the movements of the planet Venus in the sky. The discontinuous movements of Venus relate to both mythology as well as Inanna's dual nature. In ''Inanna's Descent to the Underworld'', unlike any other deity, Inanna is able to descend into the netherworld and return to the heavens. The planet Venus appears to make a similar descent, setting in the West and then rising again in the East. An introductory hymn describes Inanna leaving the heavens and heading for ''Kur'', what could be presumed to be, the mountains, replicating the rising and setting of Inanna to the West. In '' Inanna and Shukaletuda'' and ''
Inanna's Descent into the Underworld Inanna is the ancient Mesopotamian goddess of war, love, and fertility. She is also associated with political power, divine law, sensuality, and procreation. Originally worshipped in Sumer, she was known by the Akkadians, Babylonians, and Assy ...
'' appear to parallel the motion of the planet Venus. In ''Inanna and Shukaletuda'', Shukaletuda is described as scanning the heavens in search of Inanna, possibly searching the eastern and western horizons. In the same myth, while searching for her attacker, Inanna herself makes several movements that correspond with the movements of Venus in the sky. Via
Mesopotamia Mesopotamia is a historical region of West Asia situated within the Tigris–Euphrates river system, in the northern part of the Fertile Crescent. Today, Mesopotamia is known as present-day Iraq and forms the eastern geographic boundary of ...
n influence, it is possible that the
Ancient Egypt Ancient Egypt () was a cradle of civilization concentrated along the lower reaches of the Nile River in Northeast Africa. It emerged from prehistoric Egypt around 3150BC (according to conventional Egyptian chronology), when Upper and Lower E ...
ians and
Greeks Greeks or Hellenes (; , ) are an ethnic group and nation native to Greece, Greek Cypriots, Cyprus, Greeks in Albania, southern Albania, Greeks in Turkey#History, Anatolia, parts of Greeks in Italy, Italy and Egyptian Greeks, Egypt, and to a l ...
knew that the morning star and the evening star were one and the same as early as the second millennium BC—or the Late Period at the latest. The Egyptians knew the morning star as and the evening star as . They depicted Venus at first as a phoenix or
heron Herons are long-legged, long-necked, freshwater and coastal birds in the family Ardeidae, with 75 recognised species, some of which are referred to as egrets or bitterns rather than herons. Members of the genus ''Botaurus'' are referred to as bi ...
(see
Bennu Bennu () is an ancient Egyptian deity linked with the Sun, creation, and rebirth. He may have been the original inspiration for the phoenix legends that developed in Greek mythology. Roles According to Egyptian mythology, Bennu was a self-crea ...
), calling it 'the crosser' or 'star with crosses', associating it with
Osiris Osiris (, from Egyptian ''wikt:wsjr, wsjr'') was the ancient Egyptian deities, god of fertility, agriculture, the Ancient Egyptian religion#Afterlife, afterlife, the dead, resurrection, life, and vegetation in ancient Egyptian religion. He was ...
, and later depicting it as two-headed (with human or falcon heads), and associated it with
Horus Horus (), also known as Heru, Har, Her, or Hor () in Egyptian language, Ancient Egyptian, is one of the most significant ancient Egyptian deities who served many functions, most notably as the god of kingship, healing, protection, the sun, and t ...
, son of
Isis Isis was a major goddess in ancient Egyptian religion whose worship spread throughout the Greco-Roman world. Isis was first mentioned in the Old Kingdom () as one of the main characters of the Osiris myth, in which she resurrects her sla ...
(which during the even later
Hellenistic period In classical antiquity, the Hellenistic period covers the time in Greek history after Classical Greece, between the death of Alexander the Great in 323 BC and the death of Cleopatra VII in 30 BC, which was followed by the ascendancy of the R ...
was together with
Hathor Hathor (, , , Meroitic language, Meroitic: ') was a major ancient Egyptian deities, goddess in ancient Egyptian religion who played a wide variety of roles. As a sky deity, she was the mother or consort of the sky god Horus and the sun god R ...
identified with
Aphrodite Aphrodite (, ) is an Greek mythology, ancient Greek goddess associated with love, lust, beauty, pleasure, passion, procreation, and as her syncretism, syncretised Roman counterpart , desire, Sexual intercourse, sex, fertility, prosperity, and ...
). The Greeks used the names , meaning 'light-bringer' (whence the element
phosphorus Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...
; alternately , meaning 'dawn-bringer'), for the morning star, and , meaning 'Western one', for the evening star, both children of dawn
Eos In ancient Greek mythology and Ancient Greek religion, religion, Eos (; Ionic Greek, Ionic and Homeric Greek ''Ēṓs'', Attic Greek, Attic ''Héōs'', "dawn", or ; Aeolic Greek, Aeolic ''Aúōs'', Doric Greek, Doric ''Āṓs'') is the go ...
and therefore grandchildren of Aphrodite. Though by the Roman era they were recognized as one celestial object, known as "the star of
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 ...
", the traditional two Greek names continued to be used, though usually translated to Latin as and . Classical poets such as
Homer Homer (; , ; possibly born ) was an Ancient Greece, Ancient Greek poet who is credited as the author of the ''Iliad'' and the ''Odyssey'', two epic poems that are foundational works of ancient Greek literature. Despite doubts about his autho ...
,
Sappho Sappho (; ''Sapphṓ'' ; Aeolic Greek ''Psápphō''; ) was an Ancient Greek poet from Eresos or Mytilene on the island of Lesbos. Sappho is known for her lyric poetry, written to be sung while accompanied by music. In ancient times, Sapph ...
,
Ovid Publius Ovidius Naso (; 20 March 43 BC – AD 17/18), known in English as Ovid ( ), was a Augustan literature (ancient Rome), Roman poet who lived during the reign of Augustus. He was a younger contemporary of Virgil and Horace, with whom he i ...
and
Virgil Publius Vergilius Maro (; 15 October 70 BC21 September 19 BC), usually called Virgil or Vergil ( ) in English, was an ancient Rome, ancient Roman poet of the Augustan literature (ancient Rome), Augustan period. He composed three of the most fa ...
spoke of the star and its light. Poets such as
William Blake William Blake (28 November 1757 – 12 August 1827) was an English poet, painter, and printmaker. Largely unrecognised during his life, Blake has become a seminal figure in the history of the Romantic poetry, poetry and visual art of the Roma ...
,
Robert Frost Robert Lee Frost (March26, 1874January29, 1963) was an American poet. Known for his realistic depictions of rural life and his command of American Colloquialism, colloquial speech, Frost frequently wrote about settings from rural life in New E ...
,
Letitia Elizabeth Landon Letitia Elizabeth Landon (14 August 1802 – 15 October 1838) was an English poet and novelist, better known by her initials L.E.L. Landon's writings are emblematic of the transition from Romanticism to Victorian literature. Her first major b ...
,
Alfred Lord Tennyson Alfred Tennyson, 1st Baron Tennyson (; 6 August 1809 – 6 October 1892) was an English poet. He was the Poet Laureate during much of Queen Victoria's reign. In 1829, Tennyson was awarded the Chancellor's Gold Medal at Cambridge for one of ...
and
William Wordsworth William Wordsworth (7 April 177023 April 1850) was an English Romantic poetry, Romantic poet who, with Samuel Taylor Coleridge, helped to launch the Romanticism, Romantic Age in English literature with their joint publication ''Lyrical Balla ...
wrote odes to it. The composer
Holst Gustav Theodore Holst (born Gustavus Theodore von Holst; 21 September 1874 – 25 May 1934) was an English composer, arranger and teacher. Best known for his orchestral suite ''The Planets'', he composed many other works across a range ...
included it as the second movement of his ''
The Planets ''The Planets'', Op. 32, is a seven- movement orchestral suite by the English composer Gustav Holst, written between 1914 and 1917. In the last movement the orchestra is joined by a wordless female chorus. Each movement of the suite is name ...
'' suite. In India, the name for Venus in Sanskrit was , meaning 'the planet Shukra'—in reference to
Shukra Shukra (, ) is a Sanskrit word that means "clear" or "bright". It also has other meanings, such as the name of a sage who was the preceptor of the asuras and taught them the Vedas. In medieval mythology and Hindu astrology, the word refers to ...
, a powerful saint. As appears in Vedic astrology, the Sanskrit name ''Shukra'' means 'clear, pure' or 'brightness, clearness'. One of the nine
Navagraha The navagraha are nine heavenly bodies and deities that influence human life on Earth according to Hinduism and Hindu mythology. The term is derived from ''nava'' ( "nine") and ''graha'' ( "planet, seizing, laying hold of, holding"). The nine part ...
, it is held to affect wealth, pleasure and reproduction; it was the son of
Bhrgu Bhrigu (, ) is a rishi in Hindu tradition. He is one of the seven great sages, the Saptarshis, and one of the many Prajapatis (the facilitators of creation) created by Brahma. He was the first compiler of predictive astrology and also the aut ...
, preceptor of the Daityas, and guru of the Asuras. The English name ''Venus'' stems originally from the
ancient Roman In modern historiography, ancient Rome is the Roman people, Roman civilisation from the founding of Rome, founding of the Italian city of Rome in the 8th century BC to the Fall of the Western Roman Empire, collapse of the Western Roman Em ...
s. Romans named Venus after their goddess of love, who in turn was based on the
ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...
love goddess
Aphrodite Aphrodite (, ) is an Greek mythology, ancient Greek goddess associated with love, lust, beauty, pleasure, passion, procreation, and as her syncretism, syncretised Roman counterpart , desire, Sexual intercourse, sex, fertility, prosperity, and ...
, who was herself based on the similar
Sumerian religion Sumerian religion was the religion practiced by the people of Sumer, the first literate civilization found in recorded history and based in ancient Mesopotamia, and what is modern day Iraq. The Sumerians widely regarded their divinities as res ...
goddess
Inanna Inanna is the List of Mesopotamian deities, ancient Mesopotamian goddess of war, love, and fertility. She is also associated with political power, divine law, sensuality, and procreation. Originally worshipped in Sumer, she was known by the Akk ...
(which is Ishtar in
Akkadian religion Ancient Mesopotamian religion encompasses the religious beliefs (concerning the gods, creation and the cosmos, the origin of man, and so forth) and practices of the civilizations of ancient Mesopotamia, particularly Sumer, Akkad, Assyria and B ...
), all of whom were associated with the planet. The weekday of the planet and these goddesses is
Friday Friday is the day of the week between Thursday and Saturday. In countries that adopt the traditional "Sunday-first" convention, it is the sixth day of the week. In countries adopting the ISO 8601-defined "Monday-first" convention, it is the fifth ...
, named after the Germanic goddess
Frigg Frigg (; Old Norse: ) is a goddess, one of the Æsir, in Germanic mythology. In Norse mythology, the source of most surviving information about her, she is associated with marriage, prophecy, clairvoyance and motherhood, and dwells in the wetl ...
, who has been associated with the Roman goddess Venus. In Chinese, the planet is called ''Jinxing'' (); of the five elements of traditional Chinese philosophy, Venus was historically associated with
metal A metal () is a material that, when polished or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, electricity and thermal conductivity, heat relatively well. These properties are all associated wit ...
. These traditions are shared among modern
Chinese Chinese may refer to: * Something related to China * Chinese people, people identified with China, through nationality, citizenship, and/or ethnicity **Han Chinese, East Asian ethnic group native to China. **'' Zhonghua minzu'', the supra-ethnic ...
,
Japanese Japanese may refer to: * Something from or related to Japan, an island country in East Asia * Japanese language, spoken mainly in Japan * Japanese people, the ethnic group that identifies with Japan through ancestry or culture ** Japanese diaspor ...
,
Korean Korean may refer to: People and culture * Koreans, people from the Korean peninsula or of Korean descent * Korean culture * Korean language **Korean alphabet, known as Hangul or Korean **Korean dialects **See also: North–South differences in t ...
and
Vietnamese Vietnamese may refer to: * Something of, from, or related to Vietnam, a country in Southeast Asia * Vietnamese people, or Kinh people, a Southeast Asian ethnic group native to Vietnam ** Overseas Vietnamese, Vietnamese people living outside Vietna ...
cultures, including a name for the planet literally meaning 'metal star' () in each language. The
Maya Maya may refer to: Ethnic groups * Maya peoples, of southern Mexico and northern Central America ** Maya civilization, the historical civilization of the Maya peoples ** Mayan languages, the languages of the Maya peoples * Maya (East Africa), a p ...
considered Venus to be the most important celestial body after the Sun and Moon. They called it , or , 'the Great Star'. The cycles of Venus were important to their calendar and were described in some of their books, such as the ''
Maya Codex of Mexico The ''Maya Codex of Mexico'' (MCM) is a Maya screenfold codex manuscript of a pre-Columbian type. Long known as the ''Grolier Codex'' or ''Sáenz Codex'', in 2018 it was officially renamed the ''Códice Maya de México'' (CMM) by the National In ...
'' and ''
Dresden Codex The ''Dresden Codex'' is a Maya book, which was believed to be the oldest surviving book written in the Americas, dating to the 11th or 12th century. However, in September 2018 it was proven that the Maya Codex of Mexico, previously known as th ...
''. The
flag of Chile The flag of Chile consists of two equal-height horizontal bands of white and red, with a blue square the same height as the white band in the canton (flag), canton, which bears a white five-pointed star in its center. It was adopted on 18 Octo ...
(, 'Lone Star') depicts Venus.


Modern culture

The impenetrable Venusian cloud cover gave science fiction writers free rein to speculate on conditions at its surface; all the more so when early observations showed that not only was it similar in size to Earth, it possessed a substantial atmosphere. Closer to the Sun than Earth, the planet was often depicted as warmer, but still
habitable Habitability is the adequacy of an environment for human living. Where housing is concerned, there are generally local ordinances which define habitability. If a residence complies with those laws, it is said to be habitable. In extreme environ ...
by humans. The genre reached its peak between the 1930s and 1950s, at a time when science had revealed some aspects of Venus, but not yet the harsh reality of its surface conditions. Findings from the first missions to Venus showed reality to be quite different and brought this particular genre to an end. As scientific knowledge of Venus advanced, science fiction authors tried to keep pace, particularly by conjecturing human attempts to terraform Venus.


Symbols

frameless, left, 80px The symbol of a circle with a small cross beneath is the so-called
Venus symbol Planetary symbols are used in astrological symbol, astrology and traditionally in astronomical symbol, astronomy to represent a classical planet (which includes the Sun and the Moon) or one of the modern planets. The classical symbols were also use ...
, gaining its name for being used as the
astronomical symbol Astronomical symbols are abstract pictorial symbols used to represent astronomical objects, theoretical constructs and observational events in Western culture, European astronomy. The earliest forms of these symbols appear in Greek papyrus tex ...
for Venus. The symbol is of
ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...
origin, and represents more generally
femininity Femininity (also called womanliness) is a set of attributes, behaviors, and Gender roles, roles generally associated with women and girls. Femininity can be understood as Social construction of gender, socially constructed, and there is also s ...
, adopted by biology as
gender symbol Gender symbols on a public toilet in Switzerland, alt=Image shows male and female symbols incised deeply A gender symbol is a pictogram or glyph used to represent sex and gender, for example in biology and medicine, in genealogy, or in the socio ...
for female, like the
Mars symbol Planetary symbols are used in astrology and traditionally in astronomy to represent a classical planet (which includes the Sun and the Moon) or one of the modern planets. The classical symbols were also used in alchemy for the seven metals know ...
for male and sometimes the Mercury symbol for hermaphrodite. This gendered association of Venus and Mars has been used to pair them heteronormatively, describing women and men stereotypically as being so different that they can be understood as coming from different planets, an understanding popularized in 1992 by the book titled ''Men Are from Mars, Women Are from Venus''. The Venus symbol was also used in Western alchemy representing the element copper (like the symbol of Mercury is also the symbol of the element mercury), and since polished copper has been used for mirrors from antiquity the symbol for Venus has sometimes been called Venus mirror, representing the mirror of the goddess, although this origin has been discredited as an unlikely origin. Besides the Venus symbol, many other symbols have been associated with Venus, other common ones are the star and crescent, crescent or particularly the star, as with the Star of Ishtar.


See also

* Outline of Venus * List of gravitationally rounded objects of the Solar System#Planets, Physical properties of planets in the Solar System * Venus zone


Notes


References

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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 ...
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J. , last2=Del Genio , first2=Anthony D. , journal=Journal of Geophysical Research: Planets , publisher=American Geophysical Union (AGU) , volume=125 , issue=5 , year=2020 , issn=2169-9097 , doi=10.1029/2019je006276 , arxiv=2003.05704 , bibcode=2020JGRE..12506276W {{cite journal , title=Was Venus the first habitable world of our solar system? , last1=Way , first1=M. J. , last2=Del Genio , first2=Anthony D. , last3=Kiang , first3=Nancy Y. , last4=Sohl , first4=Linda E. , last5=Grinspoon , first5=David H. , last6=Aleinov , first6=Igor , last7=Kelley , first7=Maxwell , last8=Clune , first8=Thomas , journal=Geophysical Research Letters , publisher=American Geophysical Union (AGU) , volume=43 , issue=16 , date=28 August 2016 , pages=8376–8383 , issn=0094-8276 , doi=10.1002/2016gl069790 , pmid=28408771 , pmc=5385710 , arxiv=1608.00706 , bibcode=2016GeoRL..43.8376W {{cite web , title=NASA Study: Massive Volcanism May Have Altered Ancient Venus' Climate , last=Steigerwald , first=Bill , website=NASA , date=2 November 2022 , url=http://www.nasa.gov/feature/goddard/2022/venus-volcanic-climate-change , access-date=5 May 2023 , archive-date=10 May 2023 , archive-url=https://web.archive.org/web/20230510213318/https://www.nasa.gov/feature/goddard/2022/venus-volcanic-climate-change/ , url-status=live {{cite web , title=Venus' Atmosphere: Composition, Climate and Weather , last=Tillman , first=Nola Taylor , website=Space.com , date=18 October 2018 , url=https://www.space.com/18527-venus-atmosphere.html , access-date=9 May 2023 , archive-date=9 May 2023 , archive-url=https://web.archive.org/web/20230509122404/https://www.space.com/18527-venus-atmosphere.html , url-status=live {{cite web , title=Why Is Venus So Bright? Here's How Its Proximity to Earth, Highly Reflected Clouds Affects It , last=Davis , first=Margaret , website=Science Times , date=14 July 2021 , url=https://www.sciencetimes.com/articles/32272/20210714/why-venus-bright-heres-proximity-earth-highly-reflected-clouds-affects.htm , access-date=11 June 2023 , archive-date=13 December 2022 , archive-url=https://web.archive.org/web/20221213203043/https://www.sciencetimes.com/articles/32272/20210714/why-venus-bright-heres-proximity-earth-highly-reflected-clouds-affects.htm , url-status=live {{cite web , title=Venus and Earth: worlds apart – Transit of Venus blog , website=ESA Blog Navigator – Navigator page for active ESA blogs , date=31 May 2012 , url=https://blogs.esa.int/venustransit/2012/05/31/venus-and-earth-worlds-apart/ , access-date=11 June 2023 , archive-date=11 June 2023 , archive-url=https://web.archive.org/web/20230611201608/https://blogs.esa.int/venustransit/2012/05/31/venus-and-earth-worlds-apart/ , url-status=live {{cite journal , title=The Unveiling of Venus: Hot and Stifling , journal=Science News , date=19 June 1976 , volume=109 , issue=25 , pages=388–389 , jstor=3960800 , doi=10.2307/3960800 , quote=100 watts per square meter ... 14,000 lux ... corresponds to ... daytime with overcast clouds


Further reading

* {{cite journal , last1=O'Rourke , first1=Joseph G. , last2=Wilson , first2=Colin F. , last3=Borrelli , first3=Madison E. , last4=Byrne , first4=Paul K. , last5=Dumoulin , first5=Caroline , last6=Ghail , first6=Richard , last7=Gülcher , first7=Anna J. P. , last8=Jacobson , first8=Seth A. , last9=Korablev , first9=Oleg , last10=Spohn , first10=Tilman , last11=Way , first11=M. J. , last12=Weller , first12=Matt , last13=Westall , first13=Frances , title=Venus, the Planet: Introduction to the Evolution of Earth's Sister Planet , journal=Space Science Reviews , date=6 February 2023 , volume=219 , issue=1 , pages=10 , doi=10.1007/s11214-023-00956-0 , bibcode=2023SSRv..219...10O , url=https://link.springer.com/article/10.1007/s11214-023-00956-0 , access-date=6 February 2025 , language=en , issn=1572-9672, hdl=20.500.11850/598198 , hdl-access=free * {{cite journal , last1=Widemann , first1=Thomas , last2=Smrekar , first2=Suzanne E. , last3=Garvin , first3=James B. , last4=Straume-Lindner , first4=Anne Grete , last5=Ocampo , first5=Adriana C. , last6=Schulte , first6=Mitchell D. , last7=Voirin , first7=Thomas , last8=Hensley , first8=Scott , last9=Dyar , first9=M. Darby , last10=Whitten , first10=Jennifer L. , last11=Nunes , first11=Daniel C. , last12=Getty , first12=Stephanie A. , last13=Arney , first13=Giada N. , last14=Johnson , first14=Natasha M. , last15=Kohler , first15=Erika , last16=Spohn , first16=Tilman , last17=O'Rourke , first17=Joseph G. , last18=Wilson , first18=Colin F. , last19=Way , first19=Michael J. , last20=Ostberg , first20=Colby , last21=Westall , first21=Frances , last22=Höning , first22=Dennis , last23=Jacobson , first23=Seth , last24=Salvador , first24=Arnaud , last25=Avice , first25=Guillaume , last26=Breuer , first26=Doris , last27=Carter , first27=Lynn , last28=Gilmore , first28=Martha S. , last29=Ghail , first29=Richard , last30=Helbert , first30=Jörn , last31=Byrne , first31=Paul , last32=Santos , first32=Alison R. , last33=Herrick , first33=Robert R. , last34=Izenberg , first34=Noam , last35=Marcq , first35=Emmanuel , last36=Rolf , first36=Tobias , last37=Weller , first37=Matt , last38=Gillmann , first38=Cedric , last39=Korablev , first39=Oleg , last40=Zelenyi , first40=Lev , last41=Zasova , first41=Ludmila , last42=Gorinov , first42=Dmitry , last43=Seth , first43=Gaurav , last44=Rao , first44=C. V. Narasimha , last45=Desai , first45=Nilesh , title=Venus Evolution Through Time: Key Science Questions, Selected Mission Concepts and Future Investigations , journal=Space Science Reviews , date=October 2023 , volume=219 , issue=7 , page=56 , doi=10.1007/s11214-023-00992-w , bibcode=2023SSRv..219...56W , display-authors=1, hdl=10852/109541 , hdl-access=free


External links

{{Sister project links, commonscat=Venus (planet)
Venus profile
at NASA's Solar System Exploration site

an

at the National Space Science Data Center
Soviet Exploration of Venus
an

at Mentallandscape.com



at ''The Nine Planets''
Transits of Venus
{{Webarchive, url=https://web.archive.org/web/20120319134106/http://eclipse.gsfc.nasa.gov/transit/catalogue/VenusCatalog.html , date=19 March 2012 at NASA.gov
Geody Venus
a search engine for surface features
Interactive 3D gravity simulation of the pentagram that the orbit of Venus traces when Earth is held fixed at the centre of the coordinate system


Cartographic resources



by the U.S. Geological Survey
Gazetteer of Planetary Nomenclature: Venus
by the
International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

Venus crater database
by the Lunar and Planetary Institute
Map of Venus
by Eötvös Loránd University
Google Venus 3D
interactive map of the planet {{Venus {{Solar System {{Venus spacecraft {{Authority control {{Portal bar, Stars, Spaceflight, Outer space Venus, Planets of the Solar System Terrestrial planets Astronomical objects known since antiquity Solar System Lucifer