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Venus is the second
planet A planet is an astronomical body orbiting a star or Stellar evolution#Stellar remnants, stellar remnant that is massive enough to be Hydrostatic equilibrium, rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and ...

planet
from the
Sun The Sun is the star A star is an astronomical object consisting of a luminous spheroid of plasma (physics), plasma held together by its own gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many othe ...

Sun
. It is named after the Roman goddess of love and beauty. As the brightest natural object in Earth's
night sky The term night sky, usually associated with astronomy from Earth, refers to the nighttime appearance of astronomical object, celestial objects like stars, planets, and the Moon, which are visible in a clear sky between sunset and sunrise, when ...

night sky
after the
Moon The Moon is Earth's only natural satellite. At about one-quarter the diameter of Earth (comparable to the width of Australia (continent), Australia), it is the largest natural satellite in the Solar System relative to the size of its plane ...

Moon
, Venus can cast shadows and can be visible 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 micr ...
in broad daylight. Venus lies within
Earth's orbit Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents and islands. The remaining 70.8% is Water distribution on Eart ...
, and so never appears to venture far from the Sun, either setting in the west just after dusk or rising in the east a little while before dawn. Venus orbits the Sun every 224.7
Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents and islands. The remaining 70.8% is Water distribution on Earth, covered wi ...

Earth
days. It has a synodic day length of 117 Earth days and a sidereal rotation period of 243 Earth days. As a consequence, it takes longer to rotate about its axis than any other 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 ...

Solar System
, and does so in the opposite direction to all but
Uranus Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus, who, according to Greek mythology Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and ...

Uranus
. This means the Sun rises in the west and sets in the east. Venus does not have any
moon The Moon is Earth's only natural satellite. At about one-quarter the diameter of Earth (comparable to the width of Australia (continent), Australia), it is the largest natural satellite in the Solar System relative to the size of its plane ...

moon
s, a distinction it shares only with
Mercury Mercury usually refers to: * Mercury (planet) Mercury is the smallest planet in the Solar System and the closest to the Sun. Its orbit around the Sun takes 87.97 Earth days, the shortest of all the Sun's planets. It is named after the Roman g ...

Mercury
among the planets in the Solar System. Venus is a
terrestrial planet A terrestrial planet, telluric planet, or rocky planet, is a planet that is composed primarily of silicate Rock (geology), rocks or metals. Within the Solar System, the terrestrial planets accepted by the IAU are the inner planets closest to the Su ...
and is sometimes called Earth's "sister planet" because of their similar size, mass, proximity to the Sun, and bulk composition. It is radically different from Earth in other respects. It has the densest
atmosphere An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ''(sphaira)'', meaning 'ball' or 'sphere') is a layer or a set of layers of gases surrounding a planet or other material body, that is held in ...

atmosphere
of the four terrestrial planets, consisting of more than 96%
carbon dioxide Carbon dioxide (chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes also other symbols, such as pare ...

carbon dioxide
. The
atmospheric pressure Atmospheric pressure, also known as barometric pressure (after the barometer A barometer is a scientific instrument that is used to measure air pressure Atmospheric pressure, also known as barometric pressure (after the barometer), is the ...
at the planet's surface is about 92 times the sea level pressure of Earth, or roughly the pressure at underwater on Earth. Even though Mercury is closer to the Sun, Venus has the hottest surface of any planet in the Solar System, with a mean temperature of . Venus is shrouded by an opaque layer of highly reflective clouds of
sulfuric acid Sulfuric acid (American spelling Despite the various English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in English orthography English orthogra ...

sulfuric acid
, preventing its surface from being seen from space in
light Light or visible light is electromagnetic radiation within the portion of the electromagnetic spectrum that is visual perception, perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nan ...

light
. It may have had water oceans in the past, but these would have vaporized as the temperature rose under a
runaway greenhouse effect A runaway greenhouse effect occurs when a planet's atmosphere contains greenhouse gas A greenhouse gas (sometimes abbreviated GHG) is a gas that Absorption (electromagnetic radiation), absorbs and Emission (electromagnetic radiation), emits r ...
. The water has probably photodissociated, and the free hydrogen has been swept into interplanetary space by the
solar wind The solar wind is a stream of charged particle In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that studies matter, i ...

solar wind
because of the lack of a . As one of the brightest objects in the sky, Venus has been a major fixture in human culture for as long as records have existed. It has been made sacred to gods of many cultures, and has been a prime inspiration for writers and poets as the "morning star" and "evening star". Venus was the first planet to have its motions plotted across the sky, as early as the second millennium BC. Its proximity to Earth has made Venus a prime target for early interplanetary exploration. It was the first planet beyond Earth visited by a spacecraft (''
Venera 1 ''Venera 1'' (russian: Венера-1 meaning ''Venus 1''), also known as Venera-1VA No.2 and occasionally in the West as ''Sputnik 8'' was the first spacecraft to fly past Venus Venus is the second planet from the Sun. It is named afte ...
'' in 1961), and the first to be successfully landed on (by ''
Venera 7 Venera 7 (russian: Венера-7, lit=Venus 7) was a Soviet The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a socialist state A socialist state, socialist republic, or socialist country, sometimes ...
'' in 1970). Venusian thick clouds render observation of its surface impossible in visible spectrum, and the first detailed maps did not emerge until the arrival of the Magellan orbiter in 1991. Plans have been proposed for rovers or more complex missions, but they are hindered by Venus's hostile surface conditions. The possibility of
life on Venus The possibility of life on Venus is a subject of interest in astrobiology due to its proximity and similarities to Earth. To date, no definitive proof has been found of past or present life on Venus. Theories have decreased significantly since t ...
has long been a topic of speculation, and in recent years has received active research.


Physical characteristics

Venus is one of the four
terrestrial planet A terrestrial planet, telluric planet, or rocky planet, is a planet that is composed primarily of silicate Rock (geology), rocks or metals. Within the Solar System, the terrestrial planets accepted by the IAU are the inner planets closest to the Su ...
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". The diameter of Venus is —only less than Earth's—and its mass is 81.5% of Earth's. Conditions on the Venusian surface differ radically from those on Earth because its dense
atmosphere An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ''(sphaira)'', meaning 'ball' or 'sphere') is a layer or a set of layers of gases surrounding a planet or other material body, that is held in ...

atmosphere
is 96.5% carbon dioxide, with most of the remaining 3.5% being
nitrogen Nitrogen is the chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science ...

nitrogen
. 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 any substance at a temperature Temperature ( ) is a physical quantity that expresses hot and cold. It is the manifestation of thermal energy Thermal radiation in visible light can be seen on this hot metal ...
.


Atmosphere and climate

Venus has an extremely dense
atmosphere An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ''(sphaira)'', meaning 'ball' or 'sphere') is a layer or a set of layers of gases surrounding a planet or other material body, that is held in ...

atmosphere
composed of 96.5%
carbon dioxide Carbon dioxide (chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes also other symbols, such as pare ...

carbon dioxide
, 3.5%
nitrogen Nitrogen is the chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science ...

nitrogen
—both exist as
supercritical fluid A supercritical fluid (SCF) is any substance at a temperature Temperature ( ) is a physical quantity that expresses hot and cold. It is the manifestation of thermal energy Thermal radiation in visible light can be seen on this hot metal ...
s at the planet's surface—and traces of other gases including
sulfur dioxide Sulfur dioxide (IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering OrganizationsNational Adhering Organizations in chemistry are the organizations that work as the autho ...
. 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 oceans. The density at the surface is 65 kg/m3, 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 is the process by which radiation from a planet's atmosphere warms the planet's surface to a temperature above what it would be without this atmosphere. Radiatively active gases (i.e., greenhouse gas A greenhou ...

greenhouse effect
in the Solar System, creating surface temperatures of at least . This makes the Venusian surface hotter than
Mercury Mercury usually refers to: * Mercury (planet) Mercury is the smallest planet in the Solar System and the closest to the Sun. Its orbit around the Sun takes 87.97 Earth days, the shortest of all the Sun's planets. It is named after the Roman g ...

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 25% of Mercury's solar
irradiance In radiometry Radiometry is a set of techniques for measuring ' Measurement is the numerical quantification of the attributes of an object or event, which can be used to compare with other objects or events. The scope and application of measure ...

irradiance
. Because of its
runaway greenhouse effect A runaway greenhouse effect occurs when a planet's atmosphere contains greenhouse gas A greenhouse gas (sometimes abbreviated GHG) is a gas that Absorption (electromagnetic radiation), absorbs and Emission (electromagnetic radiation), emits r ...
, Venus been identified by scientists such as
Carl Sagan Carl Edward Sagan (; November 9, 1934December 20, 1996) was an American astronomer, planetary scientist, physical cosmology, cosmologist, Astrophysics, astrophysicist, Astrobiology, astrobiologist, author, and science communicator. His best know ...
as a warning and research object linked to
climate change Contemporary climate change includes both the global warming caused by humans, and its impacts on Earth's weather patterns. There have been previous periods of climate change, but the current changes are more rapid than any known even ...
on Earth. Venus's atmosphere is extremely rich in primordial noble gases compared to that of Earth. This enrichment indicates an early divergence from Earth in evolution. An unusually large
comet A comet is an icy, small Solar System body A small Solar System body (SSSB) is an object in the Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astr ...

comet
impact or accretion of a more massive
primary atmosphereA primary atmosphere is an atmosphere An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ''(sphaira)'', meaning 'ball' or 'sphere') is a layer or a set of layers of gases surrounding a planet or o ...
from solar nebula have been proposed to explain the enrichment. However, the atmosphere is also depleted of radiogenic argon, a proxy to mantle degassing, suggesting an early shutdown of major magmatism. Studies have suggested that billions of years ago, Venus's atmosphere could have been much more like the one surrounding the early Earth, and that there may have been substantial quantities of liquid water on the surface. After a period of 600 million to several billion years, solar forcing from rising luminosity of the Sun caused the evaporation of the original water. A runaway greenhouse effect was created once a critical level of greenhouse gases (including water) was added to its atmosphere. Although the surface conditions on Venus are no longer hospitable to any Earth-like life that may have formed before this event, there is speculation on the possibility that life exists in the upper cloud layers of Venus, up from the surface, where the temperature ranges between but the environment is acidic. The putative detection of an
absorption line A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light Light or visible light is electromagnetic radiation within the portion of the electromagnetic spect ...
of
phosphine Phosphine (IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering OrganizationsNational Adhering Organizations in chemistry are the organizations that work as the authoritat ...

phosphine
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
sulfur dioxide Sulfur dioxide (IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering OrganizationsNational Adhering Organizations in chemistry are the organizations that work as the autho ...
, or found that in fact there was no absorption line. Thermal inertia and the transfer of heat by winds in the lower atmosphere mean that the temperature of Venus's surface does not vary significantly between the planet's two hemispheres, those facing and not facing the Sun, despite Venus's extremely 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, consisting mainly of
sulfuric acid Sulfuric acid (American spelling Despite the various English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in English orthography English orthogra ...

sulfuric acid
, which is formed by
sulfur dioxide Sulfur dioxide (IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering OrganizationsNational Adhering Organizations in chemistry are the organizations that work as the autho ...
and water through a chemical reaction resulting in sulfuric acid hydrate. Additionally, the atmosphere consists of approximately 1%
ferric chloride Iron(III) chloride is the inorganic compound with the formula (). Also called ferric chloride, it is a common compound of iron in the +3 oxidation state The oxidation state, sometimes referred to as oxidation number, describes the degree of oxidat ...

ferric chloride
. Other possible constituents of the cloud particles are
ferric sulfate Iron(III) sulfate (or ferric sulfate), is a family of inorganic compound In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, molecules and ions: the ...
,
aluminium chloride Aluminium chloride (AlCl3), also known as aluminium trichloride, describe compounds with the formula AlCl3(H2O)n (n = 0 or 6). They consist of aluminium Aluminium (aluminum in American English, American and Canadian English) is a chemical e ...

aluminium chloride
and phosphoric anhydride. Clouds at different levels have different compositions and particle size distributions. These clouds reflect and scatter about 90% of the sunlight that falls on them back into space, and prevent visual observation of Venus's surface. The permanent cloud cover means that although Venus is closer than Earth to the Sun, it receives less sunlight on the ground. 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. The surface of Venus is effectively
isothermal In thermodynamics, an isothermal process is a type of thermodynamic process in which the temperature ''T'' of a Thermodynamic system, system remains constant: Δ''T'' = 0. This typically occurs when a system is in contact with an outside the ...

isothermal
; it retains a constant temperature not only between the two hemispheres but between the equator and the poles. Venus's minute
axial tilt In , axial tilt, also known as obliquity, is the angle between an object's and its al axis, or, equivalently, the angle between its ial plane and . It differs from . At an obliquity of 0 degrees, the two axes point in the same direction; i.e., ...
—less than 3°, compared to 23° on Earth—also minimises seasonal temperature variation. Altitude is one of the few factors that affect Venusian temperature. The highest point on Venus,
Maxwell Montes Maxwell Montes is a mountain A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. A mountain differs from a plateau in having a limited summit area, and is larger than a h ...
, 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 that bore a strong resemblance to terrestrial snow. This substance likely formed from 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 with the Symbol (chemistry), 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 cha ...

tellurium
to lead sulfide (
galena Galena, also called lead glance, is the natural mineral form of lead(II) sulfide Lead is a chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scienti ...

galena
). Although Venus has no seasons as such, 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 or solar magnetic activity cycle is a nearly periodic 11-year change in the Sun The Sun is the star A star is an astronomical object consisting of a luminous spheroid of plasma (physics), plasma held together by its ...
. The existence of lightning in the atmosphere of Venus has been controversial since the first suspected bursts were detected by the Soviet . In 2006–07, ''
Venus Express ''Venus Express'' (VEX) was the first Venus Venus is the second planet from the Sun. It is named after the Venus (mythology), Roman goddess of love and beauty. As List of brightest natural objects in the sky, the brightest natural object i ...
'' clearly detected whistler mode waves, the signatures of lightning. Their
intermittent In dynamical systems, intermittency is the irregular alternation of phases of apparently periodic and Chaos theory, chaotic dynamics (Pomeau–Manneville scenario, Pomeau–Manneville dynamics), or different forms of chaotic dynamics (crisis-in ...

intermittent
appearance indicates a pattern associated with weather activity. According to these measurements, the lightning rate is at least half of that on Earth, however other instruments have not detected lightning at all. The origin of any lightning remains unclear, but could originate from the clouds or volcanoes. In 2007, ''Venus Express'' discovered that a huge double atmospheric vortex exists at the south pole. ''Venus Express'' also discovered, in 2011, that an
ozone Ozone (), or trioxygen, is an inorganic molecule A molecule is an electrically Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a cha ...

ozone
layer exists high in the atmosphere of Venus. On 29 January 2013,
ESA , owner = , headquarters = Paris, Île-de-France, France , coordinates = , spaceport = Guiana Space Centre , seal = File:ESA emblem seal.png , seal_size = 130px , image = ESA Headquarters in Paris, France, 2 ...

ESA
scientists reported that the
ionosphere The ionosphere () is the ionized part of Earth's upper atmosphere, from about to altitude, a region that includes the thermosphere The thermosphere is the layer in the directly above the and below the . Within this layer of the atmosphere, ...
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 A small Solar System body (SSSB) is an object in the Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astr ...

comet
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 shapes in the atmosphere of Venus. This was considered direct evidence of the existence of perhaps the largest stationary
gravity wave In , gravity waves are waves generated in a medium or at the between two media when the of or tries to restore equilibrium. An example of such an interface is that between the and the , which gives rise to s. A gravity wave results when ...
s in the solar system.


Geography

The Venusian surface was a subject of speculation until some of its secrets were revealed by
planetary science Planetary science (or more rarely, planetology) is the scientific study of planets (including Earth), Astronomical object, celestial bodies (such as Natural satellite, moons, Asteroid, asteroids, Comets on Fire, comets) and planetary systems (in p ...
in the 20th century. ''
Venera The Venera (, , which means "Venus" in Russian) program was the name given to a series of space probe A space probe or a spaceprobe is a robotic spacecraft that doesn't Earth orbit, orbit the Earth (planet), Earth, but instead explores ...

Venera
'' 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. The ground shows evidence of extensive
volcanism Volcanism (or volcanicity) is the phenomenon of eruption of molten rock (magma Magma () is the molten or semi-molten natural material from which all igneous rock Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magma ...
, and the
sulfur Sulfur (in nontechnical British English: sulphur) is a chemical element In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: th ...

sulfur
in the atmosphere may indicate that there have been recent eruptions. 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 one of two main highland regions on the Venus planet. It is the smaller of the three "continents", and is located near the north pole. It is named after the Akkadian Empire, Akkadian goddess Ishtar. The size of Ishtar Terra is r ...
after
Ishtar Inanna is an ancient Mesopotamian goddess associated with love, beauty, sex, war, justice and political power. She was originally worshiped in Sumer Sumer ()The name is from Akkadian language, Akkadian '; Sumerian language, Sumerian '' ...

Ishtar
, the
Babylon ''Bābili(m)'' * sux, 𒆍𒀭𒊏𒆠 * arc, 𐡁𐡁𐡋 ''Babil'' * grc-gre, Βαβυλών ''Babylṓn'' * he, בָּבֶל ''Bavel'' * peo, 𐎲𐎠𐎲𐎡𐎽𐎢 ''Bābiru'' * elx, 𒀸𒁀𒉿𒇷 ''Babili'' *Kassite The Kassites ...

Babylon
ian goddess of love, and is about the size of Australia.
Maxwell Montes Maxwell Montes is a mountain A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. A mountain differs from a plateau in having a limited summit area, and is larger than a h ...
, the highest mountain on Venus, lies on Ishtar Terra. Its peak is above the Venusian average surface elevation. The southern continent is called
Aphrodite Terra Aphrodite Terra is one of two continental regions on the planet Venus (the other being Ishtar Terra). Aphrodite Terra, the Greek name for the goddess Venus, is about the size of half the continent of Africa, and is to be found near the equator o ...
, after the
Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately 10.7 million as of ...
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. The absence of evidence of
lava Lava is magma Magma () is the molten or semi-molten natural material from which all s are formed. Magma is found beneath the surface of the , and evidence of has also been discovered on other and some s. Besides molten rock, magma may al ...

lava
flow accompanying any of the visible
caldera A caldera is a large cauldron A cauldron (or caldron) is a large cookware and bakeware, pot (kettle) for cooking or boiling over an open fire, with a lid and frequently with an arc-shaped hanger and/or integral handles or feet. There is a r ...

caldera
s remains an enigma. The planet has few
impact crater An impact crater is an approximately circular depression (geology), depression in the surface of a planet, natural satellite, moon, or other solid body in the Solar System or elsewhere, formed by the hypervelocity collision, impact of a smaller ...

impact crater
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 mathematician A mathematician is someone who uses an extensive knowledge of mathematics Mathematics (from Greek: ) includes the study of such topics as num ...

James Clerk Maxwell
, and highland regions
Alpha Regio Alpha Regio is a region of the planet Venus extending for about 1500 kilometers centered at 22°S, 5°E. It was discovered and named by Richard Goldstein (astronomer), Richard Goldstein in 1964. The name was approved by the International Astrono ...

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 given ...
, 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 ap ...

Ovda Regio
. The last three features were named before the current system was adopted by the
International Astronomical Union The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a Non-governmental organization, nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting ...
, the body which oversees
planetary nomenclature, 1st edition (1881), predating IAU conventions 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, ...
. The longitude of physical features on Venus are expressed relative to its
prime meridian #REDIRECT Prime meridian#REDIRECT Prime meridian A prime meridian is the meridian (geography), meridian (a line of longitude) in a geographic coordinate system at which longitude is defined to be 0°. Together, a prime meridian and its anti-meri ...

prime 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 on
Sedna Planitia Sedna Planitia is a large lowland area of Venus Venus is the second planet from the Sun. It is named after the Venus (mythology), Roman goddess of love and beauty. As List of brightest natural objects in the sky, the brightest natural objec ...
. 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 Venus is the second planet from the Sun. It is named after the Venus (mythology), Roman goddess of love and beauty. As List of brightest natural objects in the sky, the brightest natural object i ...
'' and ''Magellan'', indicating a different, possibly a more
felsic In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid Earth, the rock (geology), rocks of which it is composed, and the processes ...
, mineral assemblage. The mechanism to generate a large amount of felsic crust usually requires the presence of water ocean and
plate tectonics Plate tectonics (from the la, label=Late Latin Late Latin ( la, Latinitas serior) is the scholarly name for the written Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. L ...
, implying that habitable condition had existed on early Venus. However, the nature of tessera terrains is far from certain.


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 IslandBig Island may refer to: Canada ; Newfoundland and Labrador * Big Island (Newfoundland and Labrador) ; Nova Scotia * Big Island, Nova Scotia, a peninsula in Pictou County ; Nunavut *Big Island (Hudson Bay, Nunavut), near Puvirnituq, Quebec *Big ...
of Hawaii. This is not because Venus is more volcanically active than Earth, but because its crust is older and is not subject the same
erosion In earth science Earth science or geoscience includes all fields of natural science Natural science is a branch of science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific ...

erosion
process. Earth's
oceanic crust The oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates This is a list of tectonic plates on Earth's surface. Tectonic plates are pieces of Earth's crust 350px, Plates in the crust of Earth Earth's crust i ...
is continually recycled by
subduction Subduction is a geological process in which the oceanic lithosphere A lithosphere ( grc, λίθος [] for "rocky", and [] for "sphere") is the rigid, outermost shell of a terrestrial planet, terrestrial-type planet or natural satellite. O ...

subduction
at the boundaries of
tectonic plate This is a list of tectonic plates on Earth's surface Earth is the third planet A planet is an astronomical body orbiting a star or Stellar evolution#Stellar remnants, stellar remnant that is massive enough to be Hydrostatic equilibri ...
s, and has an average age of about a hundred 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 a rupture in the crust of a planetary-mass object A planet is an astronomical body orbit In physics, an orbit is the gravitationally curved trajectory of an physical body, object, such as the trajectory of a planet ar ...

volcanic
activity on Venus.
Sulfur dioxide Sulfur dioxide (IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering OrganizationsNational Adhering Organizations in chemistry are the organizations that work as the autho ...
concentrations in the atmosphere dropped by a factor of 10 between 1978 and 1986, jumped in 2006, and again declined 10-fold. This may mean that levels had been boosted several times by large volcanic eruptions. It has also 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 Several types of volcanic eruptions—during which lava, tephra (Volcanic ash, ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from ...
). In January 2020, astronomers reported evidence that suggests that Venus is currently , specifically the detection of
olivine The mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. ...

olivine
, a volcanic product that would weather quickly on the planet's surface. 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 , near the shield volcano Maat Mons. 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 .


Craters

Almost a thousand impact craters on Venus are 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 Physics is the that studies , its , its and behavior through , and the related entities of and . "Physical science is that department of knowledge which relates to the order of nature, or, in other words, to the regular ...
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 seismic data or knowledge of its
moment of inertia The moment of inertia, otherwise known as the mass moment of inertia, angular mass, second moment of mass, or most accurately, rotational inertia, of a rigid body In physics Physics is the natural science that studies matter, its ...

moment of inertia
, little direct information is 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 they share a similar internal structure: a
core Core or cores may refer to: Science and technology * Core (anatomy) In common parlance, the core of the body is broadly considered to be the torso. Functional movements are highly dependent on this part of the body, and lack of core muscular dev ...
,
mantle Mantle may refer to: *Mantle (geology) A mantle is a layer inside a planetary body A planet is an astronomical body Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws of the stars) is a n ...
, 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. This is in line with the first observation-based estimate of 3,500 km. The principal difference between the two planets is the lack of evidence for
plate tectonics Plate tectonics (from the la, label=Late Latin Late Latin ( la, Latinitas serior) is the scholarly name for the written Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. L ...
on Venus, possibly because its crust is too strong to
subduct Subduction is a geological process in which the oceanic lithosphere A lithosphere ( grc, λίθος [] for "rocky", and [] for "sphere") is the rigid, outermost shell of a terrestrial planet, terrestrial-type planet or natural satellite. O ...

subduct
without water to make it less
viscous The viscosity of a fluid In physics Physics is the that studies , its , its and behavior through , and the related entities of and . "Physical science is that department of knowledge which relates to the order of nature, or, ...
. 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 is a vector field In vector calculus and physics, a vector field is an assignment of a vector to each point in a subset of space. For instance, a vector field in the plane can be visualised as a collection of arrows with ...

magnetic field
. Instead, Venus may lose its internal heat in periodic major resurfacing events.


Magnetic field and core

In 1967, ''
Venera 4 Venera 4 (russian: Венера-4, lit=Venus-4), also designated 4V-1 No.310, was a Space probe, probe in the Soviet Venera program for the exploration of Venus. The probe comprised a Lander (spacecraft), lander, designed to enter the Venusian a ...
'' found Venus's
magnetic field A magnetic field is a vector field In vector calculus and physics, a vector field is an assignment of a vector to each point in a subset of space. For instance, a vector field in the plane can be visualised as a collection of arrows with ...

magnetic field
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 Earth's upper atmosphere, from about to altitude, a region that includes the thermosphere The thermosphere is the layer in the directly above the and below the . Within this layer of the atmosphere, ...
and the
solar wind The solar wind is a stream of charged particle In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that studies matter, i ...

solar wind
, rather than by an internal
dynamo A dynamo is an that creates using a . Dynamos were the first electrical generators capable of delivering power for industry, and the foundation upon which many other later devices were based, including the , the , and the . Today, the simple ...

dynamo
as in the Earth's
core Core or cores may refer to: Science and technology * Core (anatomy) In common parlance, the core of the body is broadly considered to be the torso. Functional movements are highly dependent on this part of the body, and lack of core muscular dev ...
. Venus's small induced magnetosphere provides negligible protection to the atmosphere against
cosmic radiation Cosmic rays are high-energy protons and atomic nuclei that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our own galaxy, and from distant galaxies. Upon impact with Atmospher ...
. The lack of an intrinsic magnetic field at Venus was surprising, given that it is similar to Earth in size and was expected also 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 primar ...
liquid, rotation, and
convection Convection is single or multiphase fluid flow that occurs Spontaneous process, spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When t ...

convection
. 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 Heat flux of \mathbf(\mathbf) with the unit normal vector \mathbf(\mathbf) ''(blue arrows)'' at the point \mathbf multiplied by the area dS. The sum of \mathbf\cdot\mathbf dS for each patch on the surface is the flux through the surface Flux ...
through the crust. This
insulating Insulation may refer to: Thermal * Thermal insulation, use of materials to reduce rates of heat transfer ** List of insulation materials ** Building insulation, thermal insulation added to buildings for comfort and energy efficiency *** Insulated s ...

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 completely solidified. The state of the core is highly dependent on the concentration of
sulfur Sulfur (in nontechnical British English: sulphur) is a chemical element In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: th ...

sulfur
, which is unknown at present. The weak magnetosphere around Venus means that the
solar wind The solar wind is a stream of charged particle In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that studies matter, i ...

solar wind
is interacting directly with its outer atmosphere. Here, ions of hydrogen and oxygen are being created by the dissociation of water molecules from
ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior through Spacetime, ...

ultraviolet
radiation. The solar wind then supplies energy that gives some of these ions sufficient velocity 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 (or hydrogen-2, symbol or deuterium, also known as heavy hydrogen) is one of two stable isotopes The term stable isotope has a meaning similar to stable nuclide, but is preferably used when speaking of nuclides of a specific elemen ...

deuterium
to lower-mass hydrogen in the atmosphere 100 times compared to the rest of the solar system.


Orbit and rotation

Venus orbits the Sun at an average distance of about , and completes an orbit every 224.7 days. Although all
planetary orbit Planetary means relating to a planet A planet is an astronomical body orbiting a star or Stellar evolution#Stellar remnants, stellar remnant that is massive enough to be Hydrostatic equilibrium, rounded by its own gravity, is not massive enough ...
s are , Venus's orbit is currently the closest to
circular Circular may refer to: * The shape of a circle * Circular (album), ''Circular'' (album), a 2006 album by Spanish singer Vega * Circular letter (disambiguation) ** Flyer (pamphlet), a form of advertisement * Circular reasoning, a type of logical fa ...

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- center, in geometry * Eccentricity (graph theory) of a ...
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 the early climate evolution. The current near-circular orbit of Venus means that when Venus lies between Earth and the Sun in
inferior conjunction In astronomy Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws of the stars) is a natural science that studies astronomical object, celestial objects and celestial event, phenomena. It uses math ...
, it makes the closest approach to Earth of any planet at an average distance of . The planet reaches inferior conjunction every 584 days, on average. 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 40millionkm; then there are none for about 60,158 years. All the planets in the Solar System orbit the Sun in an
anticlockwise Two-dimensional rotation A rotation is a circular movement of an object around a center (or point) of rotation. The plane (geometry), geometric plane along which the rotation occurs is called the ''rotation plane'', and the imaginary line e ...
direction as viewed from above Earth's north pole. Most planets also rotate on their axes in an anti-clockwise direction, but Venus rotates clockwise in retrograde rotation once every 243 Earth days—the slowest rotation of any planet. Because its rotation is so slow, Venus is very close to spherical. A Venusian
sidereal day Sidereal time () is a timekeeping system that astronomers use to locate celestial objects. Using sidereal time, it is possible to easily point a telescope to the proper coordinates in the night sky The term night sky, usually associated ...
thus lasts longer than a Venusian year (243 versus 224.7 Earth days). Venus's equator rotates at , whereas Earth's rotates at . 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 rotation period, 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 ...
on Venus is significantly shorter than the sidereal day, at 116.75 Earth days (making the Venusian solar day shorter than
Mercury Mercury usually refers to: * Mercury (planet) Mercury is the smallest planet in the Solar System and the closest to the Sun. Its orbit around the Sun takes 87.97 Earth days, the shortest of all the Sun's planets. It is named after the Roman g ...

Mercury
's 176 Earth days — the 116-day figure is extremely close to the average number of days it takes Mercury to slip underneath the Earth in its orbit). One Venusian year is about 1.92Venusian solar days. To an observer on the surface of Venus, the Sun would rise in the west 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 The formation and evolution of the Solar System The Solar SystemCapitalization Capitalization ( North American English) or capitalisation ( British English) is writing a word with its first letter as a capital letter (uppercase letter) ...
with a different rotation period and obliquity, reaching its current state because of chaotic spin changes caused by planetary perturbations and 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 one, remaining in a stable orbit approximately 60° ahead or behind the main body near one of its Lagrangian points and . Trojans can share the ...
s: the
quasi-satellite A quasi-satellite is an object in a specific type of co-orbital configuration (1:1 orbital resonance . Conjunctions are highlighted by brief color changes. There are two Io-Europa conjunctions (green) and three Io-Ganymede conjunctions (grey) f ...
and two other temporary trojans, and . In the 17th century,
Giovanni Cassini Giovanni Domenico Cassini, also known as Jean-Dominique Cassini (8 June 1625 – 14 September 1712) was an Italian (naturalised French) mathematician, astronomer and engineer. Cassini was born in Perinaldo, near Imperia, at that time in th ...

Giovanni Cassini
reported a moon orbiting Venus, which was named
Neith Neith ( grc-koi, Νηΐθ, a borrowing of the Demotic (Egyptian), Demotic form egy, nt, likely originally to have been nrt "she is the terrifying one"; Coptic language, Coptic: ⲛⲏⲓⲧ;also spelled Nit, Net, or Neit) was an early ancient ...
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 (Caltech)The university itself only spells its short form as "Caltech"; other spellings such a"Cal Tech" and "CalTech" are incorrect. The Institute is also occasionally referred to as "CIT", most notably ...
shows Venus likely had at least one moon created by a huge
impact event An impact event is a between s causing measurable effects. Impact events have physical consequences and have been found to regularly occur in s, though the most frequent involve s, s or s and have minimal effect. When large objects impact s such ...

impact event
billions of years ago. About 10millionyears later, according to the study, another impact reversed the planet's spin direction and 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.


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 micr ...
, Venus appears as a white point of light brighter than any other planet or star (apart from the Sun). The planet's mean is −4.14 with a standard deviation of 0.31. The brightest magnitude occurs during crescent phase about one month before or after inferior conjunction. Venus fades to about magnitude −3 when it is backlit by the Sun. 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 The Solar SystemCapitalization Capitalization ( North American English) or capitalisation ( British English) is writing a word with its first letter as a capital letter (uppercase letter) and the remaining letters in ...
, it always lies within about 47° of the
Sun The Sun is the star A star is an astronomical object consisting of a luminous spheroid of plasma (physics), plasma held together by its own gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many othe ...

Sun
. 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 Mercury usually refers to: * Mercury (planet) Mercury is the smallest planet in the Solar System and the closest to the Sun. Its orbit around the Sun takes 87.97 Earth days, the shortest of all the Sun's planets. It is named after the Roman g ...

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 any perceived aerial phenomenon that cannot be immediately identified or explained. On investigation, most UFOs are identified ''Identified'' is the second studio album by Vanessa Hudgens, released ...
".


Phases

As it orbits the Sun, Venus displays like those of the
Moon The Moon is Earth's only natural satellite. At about one-quarter the diameter of Earth (comparable to the width of Australia (continent), Australia), it is the largest natural satellite in the Solar System relative to the size of its plane ...

Moon
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 * Telescope (album), ''Telescope'' (album), by Circle, 2007 * The Telescope (album), '' ...
view. The planet appears as a small and "full" disc when it is on the opposite side of the Sun (at superior
conjunction Conjunction may refer to: * Conjunction (astronomy), in which two astronomical bodies appear close together in the sky * Conjunction (astrology), astrological aspect in horoscopic astrology * Conjunction (grammar), a part of speech * Logical conjun ...

conjunction
). Venus shows a larger disc and "quarter phase" at its maximum elongations from the Sun, and appears 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.


Transits

The Venusian orbit is slightly inclined relative to Earth's orbit; thus, when the planet passes between Earth and the Sun, it usually does not cross the face of the Sun. Transits of Venus occur when the planet's
inferior conjunction In astronomy Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws of the stars) is a natural science that studies astronomical object, celestial objects and celestial event, phenomena. It uses math ...
coincides with its presence in the plane of Earth's orbit. Transits of Venus occur in cycles of with the current pattern of transits being pairs of transits separated by eight years, at intervals of about or —a pattern first discovered in 1639 by the English astronomer
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 An astronomer is a scie ...
. 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 following pair will occur in December 2117 and December 2125. The 1874 transit is the subject of the oldest film known, the 1874 ''
Passage de Venus Passage, The Passage or Le Passage may refer to: Arts and entertainment Films * ''Passage'' (2008 film), a documentary about Arctic explorers * ''Passage'' (2009 film), a short movie about three sisters * ''The Passage'' (1979 film), starring ...
''. Historically, transits of Venus were important, because they allowed astronomers to determine the size of the
astronomical unit The astronomical unit (symbol: au, or or AU) is a unit of length A unit of length refers to any arbitrarily chosen and accepted reference standard for measurement of length. The most common units in modern use are the metric system, metri ...

astronomical unit
, and hence the size of the Solar System as shown by Horrocks in 1639.
Captain Cook Captain (Royal Navy), Captain James Cook (7 November 1728Old Style and New Style dates, Old Style date: 27 October14 February 1779) was a British explorer, navigator, Cartography, cartographer, and Captain (Royal Navy), captain in the British ...

Captain Cook
's exploration of the east coast of Australia came after he had sailed to
Tahiti Tahiti (; Tahitian ; ; previously also known as Otaheite) is the largest island of the Windward group of the Society Islands The Society Islands (french: Îles de la Société, officially ''Archipel de la Société;'' ty, Tōtaiete mā) a ...

Tahiti
in 1768 to observe a transit of Venus.


Pentagram of Venus

The pentagram of Venus is the path that Venus makes as observed from
Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents and islands. The remaining 70.8% is Water distribution on Earth, covered wi ...

Earth
. Successive
inferior conjunction In astronomy Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws of the stars) is a natural science that studies astronomical object, celestial objects and celestial event, phenomena. It uses math ...
s of Venus repeat very near a 13:8 ratio (Earth orbits eight times for every 13 orbits of Venus), shifting 144° upon sequential inferior conjunctions. The 13:8 ratio is approximate. 8/13 is approximately 0.61538 while Venus orbits the Sun in 0.61519 years.


Daylight apparitions

It is most easy to see Venus in broad daylight during the time between when it is most brilliant in the evening or morning sky, approximately 37 days before and after it attains inferior conjunction, and when it is at greatest elongation east or west of the sun, which occurs approximately 70 days before and after it attains greatest elongation. Perhaps the easiest way to view Venus in broad daylight is to follow it in morning twilight, in which case it will remain visible after sunrise. Naked-eye observations of Venus during daylight hours exist in several
anecdote An ''anecdote'' is a brief, revealing account of an individual person or an incident: "a story with a point," such as to communicate an abstract idea about a person, place, or thing through the concrete details of a short narrative or to character ...

anecdote
s and records. Astronomer
Edmund Halley Edmond (or Edmund) Halley (; – ) was an English astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects su ...

Edmund Halley
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 ; co, Napulione Buonaparte. (born Napoleone di Buonaparte; 15 August 1769 – 5 May 1821) was a French military and political leader who rose to prominence during the French Revolution The French Revolution ( ) r ...

Napoleon Bonaparte
once witnessed a daytime apparition of the planet while at a reception in
Luxembourg Luxembourg ( ; lb, Lëtzebuerg ; french: link=no, Luxembourg; german: link=no, Luxemburg), officially the Grand Duchy of Luxembourg, ; french: link=no, Grand-Duché de Luxembourg ; german: link=no, Großherzogtum Luxemburg is a landlocked ...

Luxembourg
. 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 an American statesman and lawyer who served as the 16th president of the United States The president of the United States (POTUS) is the head of state and head of governme ...

Abraham Lincoln
in
Washington, D.C. ) , image_skyline = , image_caption = Clockwise from top left: the Washington Monument The Washington Monument is an obelisk within the National Mall The National Mall is a Landscape architecture, landscaped ...
, on 4March 1865. Although naked eye visibility of Venus's phases is disputed, records exist of observations of its crescent.


Ashen light

A long-standing mystery of Venus observations is the so-called
ashen light Ashen light is a hypothesised subtle glow that has been claimed to be seen on the night side of the planet Venus Venus is the second planet from the Sun. It is named after the Venus (mythology), Roman goddess of love and beauty. As List of ...
—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.


Observation and exploration


Early observation

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 . Linescan camera image (reversed to resemble an impression). A cylinder seal is a small round cylinder, typically about one inch (2 to 3 cm) in length, engraved with written characters or figurative scenes or both, used in ancient times to ...
from the
Jemdet Nasr period The Jemdet Nasr Period is an archaeological culture An archaeological culture is a recurring Assemblage (archaeology), assemblage of types of Artifact (archaeology), artifacts, buildings and monuments from a specific period and region that may con ...
and the
Venus tablet of Ammisaduqa The Venus tablet of Ammisaduqa (''Enuma Anu Enlil Enuma Anu Enlil ( ,'' The Assyrian Dictionary'', volume 7 (I/J) – ''inūma'', The Oriental Institute, Chicago 1960, s. 160. ''When he godsAnu , image=File:Cuneiform sumer dingir.svg , captio ...
from the
First Babylonian dynasty The First Babylonian Empire, or Old Babylonian Empire, is dated to BC – BC, and comes after the end of Sumerian power with the destruction of the Third Dynasty of Ur The Third Dynasty of Ur, also called the Neo-Sumerian Empire, refers to a 2 ...
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 and based in central-southern which was part of Ancient Persia (present-day and ). A small -ruled state emerged in 1894 BCE, which contained the minor administrative town of . It was merely a small provincial town dur ...
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, script 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. It is nam ...

cuneiform
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 also initially believed Venus to be two separate stars:
Phosphorus Phosphorus is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical el ...
, the morning star, and
Hesperus In Greek mythology Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the Cosmogony, origin and Cosmology#Metaphysical cosmology, nature of t ...

Hesperus
, the evening star.
Pliny the Elder #REDIRECT Pliny the Elder #REDIRECT Pliny the Elder#REDIRECT Pliny the Elder Gaius Plinius Secundus (AD 23/2479), called Pliny the Elder (), was a Roman author, a naturalist Natural history is a domain of inquiry involving organisms, includi ...

Pliny the Elder
credited the realization that they were a single object to
Pythagoras Pythagoras of Samos, or simply ; in Ionian Greek () was an ancient Ionians, Ionian Ancient Greek philosophy, Greek philosopher and the eponymous founder of Pythagoreanism. His political and religious teachings were well known in Magna Graec ...

Pythagoras
in the sixth century BC, while
Diogenes Laërtius Diogenes Laërtius ( ; grc-gre, Διογένης Λαέρτιος, Dīogénēs Lāértios; ) was a biographer of the Ancient Greece, Greek philosophers. Nothing is definitively known about his life, but his surviving ''Lives and Opinions of Emi ...
argued that
Parmenides Parmenides of Elea (; grc-gre, Παρμενίδης ὁ Ἐλεάτης; ) was a pre-Socratic Greek philosopher A philosopher is someone who practices philosophy. The term ''philosopher'' comes from the grc, φιλόσοφος, , translit ...

Parmenides
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 Lucifer is one of various figures in folklore Folklore is the expressive body of culture shared by a particular group of people; it encompasses the tradition A tradition is a belief A belief is an attitude Attitude may refer to: ...

Lucifer
, literally "Light-Bringer", and the evening aspect as , 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#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its po ...
'',
Ptolemy Claudius Ptolemy (; grc-koi, Κλαύδιος Πτολεμαῖος, , ; la, Claudius Ptolemaeus; AD) was a mathematician A mathematician is someone who uses an extensive knowledge of mathematics Mathematics (from Greek: ) includes ...
theorized that both Mercury and Venus are located between the Sun and the Earth. The 11th-century Persian astronomer
Avicenna Ibn Sina ( fa, ابن سینا), also known as Abu Ali Sina (), Pur Sina (), and often known in the West as Avicenna (;  – June 1037), was a Persian Persian may refer to: * People and things from Iran, historically called ''Persia' ...

Avicenna
claimed to have observed the
transit of Venus A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and a inferior and superior planets, superior planet, becoming visible against (and hence obscuring a small portion of) the solar disk. During ...

transit of Venus
, which later astronomers took as confirmation of Ptolemy's theory. In the 12th century, the astronomer Ibn Bajjah 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 ( fa, مراغه, az, ماراغا ), also Romanized as Marāgheh; also known as Marāgha), is an ancient city and capital of Maragheh County, East Azerbaijan Province East Azerbaijan Province ( fa, استان آذربایجان ...

Maragha
astronomer Qotb al-Din Shirazi, though this cannot be true as there were no Venus transits in Ibn Bajjah's lifetime. When the Italian physicist
Galileo Galilei Galileo di Vincenzo Bonaiuti de' Galilei ( , ; 15 February 1564 – 8 January 1642), commonly referred to as Galileo, was an astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific q ...

Galileo Galilei
first observed the planet in the early 17th century, he found it showed phases 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, and this was among 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 description of the Universe with Earth at the center. Under the geocentric model, the Sun, Moon, stars, and ...
that the Solar System was concentric and centred on Earth. The 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 An astronomer is a scie ...
and observed by him and his friend,
William Crabtree William Crabtree (1610–1644) was an astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, pla ...
, at each of their respective homes, on 4December 1639 (24 November under the
Julian calendar The Julian calendar, proposed by Julius Caesar Gaius Julius Caesar (; 12 July 100 BC – 15 March 44 BC) was a Roman Roman or Romans usually refers to: *Rome, the capital city of Italy *Ancient Rome, Roman civilization from 8th century B ...
in use at that time). The
atmosphere of Venus The atmosphere of Venus is the layer of gases surrounding Venus Venus is the second planet from the Sun. It is named after the Venus (mythology), Roman goddess of love and beauty. As List of brightest natural objects in the sky, the bright ...

atmosphere of Venus
was discovered in 1761 by Russian polymath
Mikhail Lomonosov Mikhail Vasilyevich Lomonosov (; russian: Михаил (Михайло) Васильевич Ломоносов, p=mʲɪxɐˈil vɐˈsʲilʲjɪvʲɪtɕ , a=Ru-Mikhail Vasilyevich Lomonosov.ogg; – ) was a Russian polymath A polymath ( e ...

Mikhail Lomonosov
. Venus's atmosphere was observed in 1790 by German astronomer Johann Schröter. Schröter found when the planet was a thin crescent, the cusps extended through more than 180°. He correctly surmised this was due to
scattering Scattering is a term used in physics to describe a wide range of physical processes where moving particles or radiation of some form, such as light Light or visible light is electromagnetic radiation within the portion of the electromagnetic ...

scattering
of sunlight in a dense atmosphere. Later, American astronomer observed a complete ring around the dark side of the planet when it was at
inferior conjunction In astronomy Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws of the stars) is a natural science that studies astronomical object, celestial objects and celestial event, phenomena. It uses math ...
, 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, also known as Jean-Dominique Cassini (8 June 1625 – 14 September 1712) was an Italian (naturalised French) mathematician, astronomer and engineer. Cassini was born in Perinaldo, near Imperia, at that time in th ...

Giovanni Cassini
and Schröter incorrectly estimated periods of about from the motions of markings on the planet's apparent surface.


Ground-based research

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 study of the interaction between matter and Electromagnetism, electromagnetic radiation as a function of the wavelength or frequency of the radiation. In simpler terms, spectroscopy is the precise study of color as generalize ...
,
radar Radar (radio detection and ranging) is a detection system that uses radio waves to determine the distance (''ranging''), angle, or velocity of objects. It can be used to detect aircraft, Marine radar, ships, spacecraft, guided missiles, motor ...

radar
and
ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior through Spacetime, ...

ultraviolet
observations that more of its secrets were revealed. 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 In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior ...

infrared
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 atmospheric cloud In meteorology, a cloud is an aerosol consisting of a visible mass of minute liquid drop (liquid), droplets, ice crystals, frozen crystals, or other particulates, ...

cirrus cloud
s above it. 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 redshifts, redshifted, thus pr ...
tried to measure the
Doppler shift The Doppler effect or Doppler shift (or simply Doppler, when in context) is the change in frequency of a wave in relation to an observer (physics), observer who is moving relative to the wave source. It is named after the Austrian physicist ...

Doppler shift
of light from Venus, but found he could not detect any rotation. He surmised the planet must have a much longer rotation period than had previously been thought. Later work in the 1950s showed the rotation was retrograde. 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 modern value. 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 Esperanza, Arecibo, Puerto Rico, Barrio Esperanza, Arecibo, Puerto Rico own ...

Arecibo Observatory
, and the echoes revealed two highly reflective regions, designated the
Alpha Alpha (uppercase , lowercase ; grc, ἄλφα, ''álpha'', modern pronunciation ''álfa'') is the first letter Letter, letters, or literature may refer to: Characters typeface * Letter (alphabet) A letter is a segmental symbol A s ...

Alpha
and
Beta Beta (, ; uppercase , lowercase , or cursive Cursive (also known as script, among other names) is any style of penmanship Penmanship is the technique of writing Writing is a medium of human communication that involves the represen ...
regions. The observations also revealed a bright region attributed to mountains, which was called
Maxwell Montes Maxwell Montes is a mountain A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. A mountain differs from a plateau in having a limited summit area, and is larger than a h ...
. These three features are now the only ones on Venus that do not have female names.


Exploration

The first
robotic Robotics is an interdisciplinarity, interdisciplinary branch of computer science and engineering. Robotics involves design, construction, operation, and use of robots. The goal of robotics is to design machines that can help and assist humans. ...
space probe A space probe, or simply probe, is a robotic spacecraft that doesn't Earth orbit, orbit the Earth (planet), Earth, but instead explores farther into outer space. A space probe may approach the Moon; travel through interplanetary space; planeta ...
mission to Venus and any planet was
Venera 1 ''Venera 1'' (russian: Венера-1 meaning ''Venus 1''), also known as Venera-1VA No.2 and occasionally in the West as ''Sputnik 8'' was the first spacecraft to fly past Venus Venus is the second planet from the Sun. It is named afte ...
of the Soviet
Venera program The Venera (, , which means "Venus" in Russian) program was the name given to a series of space probes developed by the Soviet Union between 1961 and 1984 to gather information about the planet Venus. Ten probes successfully landed on the s ...
launched in 1961, though it lost contact en route. The first successful mission to Venus (as well as the world's first successful
interplanetary mission Interplanetary may refer to: * Interplanetary space, the space between the planets of the Solar System * Interplanetary spaceflight, travel between planets *The interplanetary medium, the material that exists in interplanetary space *The InterPla ...
) was the
Mariner 2 Mariner 2 (Mariner-Venus 1962), an American space probe to Venus Venus is the second planet from the Sun. It is named after the Venus (mythology), Roman goddess of love and beauty. As List of brightest natural objects in the sky, the brig ...

Mariner 2
mission by the United States, passing on 14 December 1962 at above the surface of Venus and gathering data on the planet's atmosphere. On 18 October 1967, the Soviet ''
Venera 4 Venera 4 (russian: Венера-4, lit=Venus-4), also designated 4V-1 No.310, was a Space probe, probe in the Soviet Venera program for the exploration of Venus. The probe comprised a Lander (spacecraft), lander, designed to enter the Venusian a ...
'' successfully entered as the first to probe the atmosphere and deployed science experiments. ''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. The joint ''Venera 4''–''
Mariner 5 Launch of Mariner 5 Mariner 5 (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, a ...

Mariner 5
'' data were analysed by a combined Soviet–American science team in a series of colloquia over the following year, in an early example of space cooperation. In 1974, ''
Mariner 10 ''Mariner 10'' was an American robotic Robotics is an interdisciplinarity, interdisciplinary branch of computer science and engineering. Robotics involves design, construction, operation, and use of robots. The goal of robotics is to de ...

Mariner 10
'' swung by Venus to bend its path toward 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 In orbital mechanics and aerospace engineering, a gravitational slingshot, gravity assist maneuver, or swing-by is the use of the relative movement (e.g. orbit around the Sun) and gravity of a planet or other astronomical object to alter th ...
ever used, a technique which would be used by later probes, most notably ''
Voyager 1 ''Voyager 1'' is a space probe A space probe or a spaceprobe is a robotic spacecraft that doesn't Earth orbit, orbit the Earth (planet), Earth, but instead explores farther into outer space. A space probe may approach the Moon; travel ...
'' and '' 2''. In 1975, the Soviet ''
Venera 9 Venera 9 (russian: Венера-9, lit=Venus-9), manufacturer's designation: 4V-1 No. 660, was a Soviet The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a socialist state A socialist state, socialist ...
'' and '' 10'' landers transmitted the first images from the surface of Venus, which were in black and white. In 1982 the first colour images of the surface were obtained with the Soviet '' Venera 13'' and '' 14'' landers. NASA obtained additional data in 1978 with the Pioneer Venus project that consisted of two separate missions:
Pioneer Venus Orbiter The Pioneer Venus Orbiter, also known as Pioneer Venus 1 or Pioneer 12, was a mission to Venus conducted by the United States as part of the Pioneer Venus project. Launched in May 1978 atop an Atlas-Centaur rocket, the spacecraft was inserted into a ...
and Pioneer Venus Multiprobe. The successful Soviet Venera program came to a close in October 1983, when ''
Venera 15 Venera 15 (russian: Венера-15 meaning ''Venus 15'') was a spacecraft A spacecraft is a vehicle or machine designed to fly in outer space. A type of artificial satellite alt=, A full-size model of the Earth observation satel ...
'' and '' 16'' were placed in orbit to conduct detailed mapping of 25% of Venus's terrain (from the north pole to 30°N latitude) Several other missions explored Venus in the 1980s and 1990s, including ''
Vega 1 Vega 1 (along with its twin Vega 2 Vega 2 (along with Vega 1) was a Soviet Union, 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 ...

Vega 1
'' (1985), ''
Vega 2 Vega 2 (along with Vega 1) was a Soviet Union, 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 lette ...
'' (1985), ''
Galileo Galileo di Vincenzo Bonaiuti de' Galilei ( , ; 15 February 1564 – 8 January 1642), commonly referred to as Galileo, was an astronomer An astronomer is a in the field of who focuses their studies on a specific question or field o ...
'' (1990), ''
Magellan Ferdinand Magellan ( or ; pt, Fernão de Magalhães, ; es, link=no, Fernando de Magallanes, ; 4 February 1480 – 27 April 1521) was a Portuguese people, Portuguese explorer and a subject of the Habsburg Spain, Hispanic Monarchy from 1518. H ...
'' (1994), ''
Cassini–Huygens The ''Cassini–Huygens'' space-research mission ( ), commonly called ''Cassini'', involved a collaboration among NASA The National Aeronautics and Space Administration (NASA; ) is an independent agencies of the United States government, ...
'' (1998), and ''
MESSENGER Messenger, Messengers, The Messenger or The Messengers may refer to: People * Courier A courier is a company, an employee of that company or a person who delivers a message, package or letter from one place or person to another place or person. ...

MESSENGER
'' (2006). All except ''Magellan'' were gravity assists. Then, ''
Venus Express ''Venus Express'' (VEX) was the first Venus Venus is the second planet from the Sun. It is named after the Venus (mythology), Roman goddess of love and beauty. As List of brightest natural objects in the sky, the brightest natural object i ...
'' by the
European Space Agency , owner = , headquarters = Paris Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, most populous city of France, with an estimated population of 2,175,601 residents , in an area ...

European Space Agency
(ESA) entered orbit around Venus in April 2006. Equipped with seven scientific instruments, ''Venus Express'' provided unprecedented long-term observation of Venus's atmosphere. ESA concluded the ''Venus Express'' mission in December 2014. As of 2020, Japan's ''
Akatsuki may refer to: * Akatsuki (spacecraft) , also known as the Venus Climate Orbiter (VCO) and Planet-C, is a Japanese ( JAXA) space probe A space probe or a spaceprobe is a robotic spacecraft that doesn't Earth orbit, orbit the Earth (plane ...
'' is in a highly eccentric orbit around Venus since 7December 2015, and there are several probing proposals under study by
Roscosmos The State Space Corporation "Roscosmos" (russian: Государственная корпорация по космической деятельности «Роскосмос»), commonly known simply as Roscosmos (russian: Роскосмос) ...
, NASA,
ISRO The Indian Space Research Organisation (ISRO ) is the national space agency of India India, officially the Republic of India (: ), is a country in . It is the by area, the country, and the most populous in the world. Bounded by the ...
,
ESA , owner = , headquarters = Paris, Île-de-France, France , coordinates = , spaceport = Guiana Space Centre , seal = File:ESA emblem seal.png , seal_size = 130px , image = ESA Headquarters in Paris, France, 2 ...

ESA
, and the private sector (e.g. by Rocketlab).


In culture

Venus is a primary feature of the night sky, and so has been of remarkable importance in
mythology Myth is a folklore genre Folklore is the expressive body of culture shared by a particular group of people; it encompasses the tradition A tradition is a belief A belief is an Attitude (psychology), attitude that something is the ca ...
,
astrology Astrology is a pseudoscience that claims to divination, divine information about human affairs and terrestrial events by studying the movements and relative positions of Celestial objects in astrology, celestial objects. Astrology has be ...

astrology
and fiction throughout history and in different cultures. In
Sumerian religion Sumerian religion was the religion Religion is a social Social organisms, including humans, live collectively in interacting populations. This interaction is considered social whether they are aware of it or not, and whether the exchange ...
,
Inanna Inanna is an ancient Mesopotamian goddess associated with love, beauty, sex, war, justice and political power. She was originally worshiped in Sumer Sumer ()The name is from '; ''kig̃ir'', written and ,approximately "land of the ...
was associated with the planet Venus. Several hymns praise Inanna 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 Inanna is an ancient Mesopotamian goddess associated with love, beauty, sex, war, justice and political power. She was originally worshiped in Aratta and Sumer Sumer ()The name is from Akkadian '; Sumerian ''kig̃ir'', written and ...
'' and '' Inanna's Descent into the Underworld'' 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. Classical poets such as
Homer Homer (; grc, Ὅμηρος , ''Hómēros'') was an ancient Greek Ancient Greek includes the forms of the Greek language Greek ( el, label=Modern Greek Modern Greek (, , or , ''Kiní Neoellinikí Glóssa''), generally re ...

Homer
,
Sappho Sappho (; el, Σαπφώ ''Sapphō'' ; Aeolic Greek ''Psápphō''; c. 630 – c. 570 BC) was an Archaic Greek poet from Eresos or Mytilene on the island of Lesbos. Sappho is known for her Greek lyric, lyric poetry, written to be sung while a ...

Sappho
,
Ovid Pūblius Ovidius Nāsō (; 20 March 43 BC – 17/18 AD), known in English as Ovid ( ), was a Augustan literature (ancient Rome), Roman poet who lived during the reign of Augustus. He was a contemporary of the older Virgil and Horace, with whom ...

Ovid
and
Virgil Publius Vergilius Maro (; traditional dates 15 October 7021 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 ...

Virgil
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 is now considered a seminal figure in the history of the Romantic poetry, poetry and visual art of t ...

William Blake
,
Robert Frost Robert Lee Frost (March26, 1874January29, 1963) was an American poet. His work was initially published in England before it was published in the United States. Known for his realistic depictions of rural life and his command of American colloqu ...

Robert Frost
,
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. The writings of Landon are transitional between Romanticism and the Victorian Age. Her first major breakthrough ...

Letitia Elizabeth Landon
,
Alfred Lord Tennyson Alfred Tennyson, 1st Baron Tennyson (6 August 1809 – 6 October 1892) was a British poet. He was the Poet Laureate of the United Kingdom, Poet Laureate during much of Queen Victoria's reign and remains one of the most popular British poets ...
and
William Wordsworth William Wordsworth (7 April 177023 April 1850) was an English Romantic Romantic may refer to: Genres and eras * The Romantic era, an artistic, literary, musical and intellectual movement of the 18th and 19th centuries ** Romantic music, of ...

William Wordsworth
wrote odes to it. In
Chinese Chinese can refer to: * Something related to China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the List of countries and dependencies by population, world's most populous country, with a populat ...
the planet is called Jīn-xīng (金星), the golden planet of the metal element. In India Shukra Graha ("the planet Shukra") is named after the powerful saint Shukra. ''
Shukra Shukra (Sanskrit: शुक्र, IAST: ) is a word that means "clear" or "bright". It also has other meanings, such as the name of an ancient lineage of sages who counselled s in Vedic history. In medieval mythology and Hindu astrology, the ...

Shukra
'' which is used in Indian
Vedic astrology Jyotisha or Jyotishya (from Sanskrit ', from ' "light, heavenly body") is the traditional Hindu system of astrology, also known as Hindu astrology, Indian astrology and more recently Vedic astrology. The term ''Hindu astrology'' has been in u ...
means "clear, pure" or "brightness, clearness" in
Sanskrit Sanskrit (; attributively , ; nominalization, nominally , , ) is a classical language of South Asia that belongs to the Indo-Aryan languages, Indo-Aryan branch of the Indo-European languages. It arose in South Asia after its predecessor langua ...

Sanskrit
. One of the nine
Navagraha Navagraha are nine heavenly bodies and deities that influence human life on Earth according to Hinduism and Hindu astrology. The term is derived from ''nava'' ( sa, नव "nine") and ''graha'' ( sa, ग्रह "planet, seizing, laying hold of, ...

Navagraha
, it is held to affect wealth, pleasure and reproduction; it was the son of Bhrgu, preceptor of the Daityas, and guru of the Asuras. The word ''Shukra'' is also associated with semen, or generation. Venus is known as Kejora in
Indonesian Indonesian is anything of, from, or related to Indonesia, an archipelagic country in Southeast Asia. It may refer to: * Indonesians, citizens of Indonesia ** Native Indonesians, diverse groups of local inhabitants of the archipelago ** Indonesian ...

Indonesian
and Malaysian
Malay Malay may refer to: Languages * Malay language or Bahasa Melayu, a major Austronesian language spoken in Indonesia, Malaysia, Brunei and Singapore ** History of the Malay language#Old Malay, the Malay language from the 4th to the 14th century ** ...
. Modern
Chinese Chinese can refer to: * Something related to China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the List of countries and dependencies by population, world's most populous country, with a populat ...
,
Japanese Japanese may refer to: * Something from or related to Japan Japan ( ja, 日本, or , and formally ) is an island country An island country or an island nation is a country A country is a distinct territory, territorial body or ...
and
Korean Korean may refer to: People and culture * Koreans, ethnic group originating in the Korean Peninsula * Korean cuisine * Korean culture * Korean language **Korean alphabet, known as Hangul or Chosŏn'gŭl **Korean dialects and the Jeju language **S ...

Korean
cultures refer to the planet literally as the "metal star" (), based on the Five elements. The
Maya Maya may refer to: Civilizations * Maya peoples The Maya peoples () are an ethnolinguistic group of indigenous peoples Indigenous peoples, also referred to as First people, Aboriginal people, Native people, or autochthonous people, are cu ...
considered Venus to be the most important celestial body after the Sun and Moon. They called it ''Chac ek'', or ''Noh Ek''', "the Great Star". The cycles of Venus were important to their calendar and were described in some of their books such as ''Maya Codex of Mexico'' and ''
Dresden Codex The ''Dresden Codex'' is a Mayan book, the oldest surviving book written in the Americas, dating to the 11th or 12th century. The codex The codex (plural codices () was the historical ancestor of the modern book A book is a medium for ...
.'' The
Ancient Egypt Ancient Egypt was a civilization  A civilization (or civilisation) is a that is characterized by , , a form of government, and systems of communication (such as ). Civilizations are intimately associated with additional char ...

Ancient Egypt
ians and
Greeks The Greeks or Hellenes (; el, Έλληνες, ''Éllines'' ) are an ethnic group An ethnic group or ethnicity is a grouping of people A people is any plurality of person A person (plural people or persons) is a being that has cer ...
believed Venus to be two separate bodies, a morning star and an evening star. The Egyptians knew the morning star as Tioumoutiri and the evening star as Ouaiti. The Greeks used the names '' Phōsphoros'' (Φωσϕόρος), meaning "light-bringer" (whence the element
phosphorus Phosphorus is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical el ...

phosphorus
; alternately ''Ēōsphoros'' (Ἠωσϕόρος), meaning "dawn-bringer"), for the morning star, and ''
Hesperos In Greek mythology Greek mythology is the body of myth Myth is a folklore genre Folklore is the expressive body of culture shared by a particular group of people; it encompasses the tradition A tradition is a belief A belie ...

Hesperos
'' (Ἕσπερος), meaning "Western one", for the evening star."Lucifer"
in ''Encyclopaedia Britannica''
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 named after the Venus (mythology), Roman goddess of love and beauty. As List of brightest natural objects in the sky, the brightest natural object in Earth's night sky after the Moon, Venus can ...
", the traditional two Greek names continued to be used, though usually translated to Latin as and .


Modern fiction

With the invention of the telescope, the idea that Venus was a physical world and possible destination began to take form. 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 frequently depicted as warmer, but still habitable by humans. The
genre Genre () is any form or type of communication in any mode (written, spoken, digital, artistic, etc.) with socially-agreed-upon conventions developed over time. In popular usage, it normally describes a Category of being, category of literature, ...

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 the 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.


Symbol

frameless, 80px 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 is the same as that used in biology for the female sex: a circle with a small cross beneath. The Venus symbol also represents
femininity Femininity (also called womanliness or girlishness) is a set of attributes, behaviors, and roles generally associated with women A woman is an adult female Female (symbol: ♀) is the sex of an organism that produces the large non-mob ...

femininity
, and in Western
alchemy Alchemy (from Arabic Arabic (, ' or , ' or ) is a Semitic language The Semitic languages are a branch of the Afroasiatic language family originating in the Middle East The Middle East is a list of transcontinental countri ...
stood for the metal copper. Polished copper has been used for mirrors from antiquity, and the symbol for Venus has sometimes been understood to stand for the mirror of the goddess although that may not be its true origin. In the Greek
Oxyrhynchus Papyri The Oxyrhynchus Papyri are a group of manuscripts discovered during the late nineteenth and early twentieth centuries by papyrology, papyrologists Bernard Pyne Grenfell and Arthur Surridge Hunt at an ancient Landfill, rubbish dump near Oxyrhync ...
, the symbols for Venus and Mercury didn't have the cross-bar on the bottom stroke.


Habitability

Speculation on the possibility of life on Venus's surface decreased significantly after the early 1960s when it became clear that the conditions are extreme compared to those on Earth. Venus's extreme temperature and atmospheric pressure make water-based
life Life is a characteristic that distinguishes physical entities A bubble of exhaled gas in water In common usage and classical mechanics, a physical object or physical body (or simply an object or body) is a collection of matter within a ...

life
as currently known unlikely. Some scientists have speculated that thermoacidophilic
extremophile An extremophile (from Latin ' meaning "extreme" and Greek ' () meaning "love") is an organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies the ...
microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes ...
s might exist in the cooler, acidic upper layers of the Venusian atmosphere. Such speculations go back to
1967 Events January * January 1 – Canada begins a year-long celebration of the 100th anniversary of Canadian Confederation, Confederation, featuring the Expo 67 World's Fair. * January 4 – The Doors release their début album ''The Doors ( ...

1967
, when
Carl Sagan Carl Edward Sagan (; November 9, 1934December 20, 1996) was an American astronomer, planetary scientist, physical cosmology, cosmologist, Astrophysics, astrophysicist, Astrobiology, astrobiologist, author, and science communicator. His best know ...
and Harold J. Morowitz suggested in a ''
Nature Nature, in the broadest sense, is the natural, physical, material world or universe The universe ( la, universus) is all of space and time and their contents, including planets, stars, galaxy, galaxies, and all other forms of matter an ...
'' article that tiny objects detected in Venus's clouds might be organisms similar to Earth's
bacteria Bacteria (; common noun bacteria, singular bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typ ...

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 (chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes also other symbols, such as pare ...

carbon dioxide
and sunlight—the prerequisites for
photosynthesis Photosynthesis is a process used by plants and other organisms to convert Conversion or convert may refer to: Arts, entertainment, and media * Conversion (Doctor Who audio), "Conversion" (''Doctor Who'' audio), an episode of the audio drama ' ...

photosynthesis
—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 (prounounced ; la, albedo, meaning 'whiteness') is the measure of the diffuse reflection Diffuse reflection is the reflectionReflection or reflexion may refer to: Philosophy * Self-reflection Science * Reflection (physics), a comm ...

albedo
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 , latin_name = , image_name = Shield of the University of Cardiff.svg , image_size = 150px , caption = Coat of arms#REDIRECT coat of arms A coat of arms is a heraldry, heraldic communication design, visual design on an escutcheon (herald ...
announced the likely detection of
phosphine Phosphine (IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering OrganizationsNational Adhering Organizations in chemistry are the organizations that work as the authoritat ...

phosphine
, 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 30 miles 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 agency A regulatory agency or regulatory authority, is a Public benefit corporation Public-benefit corporation is a term that has different meanings in differen ...

NASA
administrator
Jim Bridenstine James Frederick Bridenstine (born June 15, 1975) is an American politician who served as the 13th Administrator Administrator or admin may refer to: Job roles Computing and internet * Database administrator, a person who is responsible for th ...
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". A statement was published on October 5, 2020, by the organizing committee of the
International Astronomical Union The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a Non-governmental organization, nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting ...
's commission F3 on astrobiology, in which the authors of the September 2020 paper about phosphine were accused of unethical behavior, and criticized for being unscientific and misleading the public. Members of that commission have since distanced themselves from the IAU statement, claiming that it had been published without their knowledge or approval. The statement was removed from the IAU website shortly thereafter. The IAU's media contact Lars Lindberg Christensen stated that IAU did not agree with the content of the letter and that it had been published by a group within the F3 commission, not IAU itself. 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 signal-noise and generated a false reading. 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 result in the detection of phosphine.


Planetary protection

The
Committee on Space Research The Committee on Space Research (COSPAR) was established in 1958 by the International Council for Scientific Unions (ICSU). Among COSPAR's objectives are the promotion of scientific research in space Space is the boundless three-dimensiona ...
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 An international non-governmental organization (INGO) is an organization which ...
. Among their responsibilities is the development of recommendations for avoiding interplanetary contamination. 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 Earth is the third planet from the Sun and the only astro ...
category two. This indicates that there is only a remote chance that spacecraft-borne contamination could compromise investigations. Though with the discovery of possible traces of indigenous life in the
atmosphere of Venus The atmosphere of Venus is the layer of gases surrounding Venus Venus is the second planet from the Sun. It is named after the Venus (mythology), Roman goddess of love and beauty. As List of brightest natural objects in the sky, the bright ...

atmosphere of Venus
, this categorization has been questioned.


Human presence

Venus is the place of the very first interplanetary human presence, mediated through robotic missions, with the first successful landings on another planet and extraterrestrial body other than the Moon. Venus was at the beginning of the
space age The Space Age is a period encompassing the activities related to the Space Race The Space Race was a 20th-century competition between two Cold War The Cold War was a period of geopolitical tension between the United States and the ...
frequently visited by
space probe A space probe, or simply probe, is a robotic spacecraft that doesn't Earth orbit, orbit the Earth (planet), Earth, but instead explores farther into outer space. A space probe may approach the Moon; travel through interplanetary space; planeta ...
s until the 1990s. Currently in orbit is
Akatsuki may refer to: * Akatsuki (spacecraft) , also known as the Venus Climate Orbiter (VCO) and Planet-C, is a Japanese ( JAXA) space probe A space probe or a spaceprobe is a robotic spacecraft that doesn't Earth orbit, orbit the Earth (plane ...
, and the
Parker Solar Probe The Parker Solar Probe (abbreviated PSP; previously Solar Probe, Solar Probe Plus or Solar Probe+) is a NASA The National Aeronautics and Space Administration (NASA; ) is an independent agencies of the United States government, independe ...

Parker Solar Probe
routinely uses Venus for
gravity assist In orbital mechanics and aerospace engineering, a gravitational slingshot, gravity assist maneuver, or swing-by is the use of the relative movement (e.g. orbit around the Sun) and gravity of a planet or other astronomical object to alter th ...
maneuvers. The only nation that has sent lander probes to the surface of Venus has been the Soviet Union, which has been used by Russian officials to call Venus a "Russian planet".


Habitation

While the surface conditions of Venus are very inhospitable, the atmospheric pressure and temperature fifty kilometres above the surface are similar to those at Earth's surface. With this in mind the Soviet engineer Sergey Zhitomirskiy (Сергей Житомирский, 1929-2004) in 1971 and more contemporarily NASA aerospace engineer Geoffrey A. Landis in 2003 suggested the use of
aerostat An aerostat (From Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is appr ...
s for crewed exploration and possibly for permanent "" in the Venusian atmosphere, an alternative to the popular idea of living on
planetary surface OSIRIS-REx collecting a surface sample from asteroid 101955 Bennu in 2020— ''(:File:OSIRIS-REX SamCam TAGSAM Event 2020-10-20.gif, Full-sized image)'' A planetary surface is where the solid (or liquid) material of the outer crust (geology), cru ...
s such as
Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, being larger than only Mercury (planet), Mercury. In English, Mars carries the name of the Mars (mythology), Roman god of war and is often referred to ...

Mars
. 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 Despite the various English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in English orthography English orthogra ...

sulfuric acid
in the atmosphere. The High Altitude Venus Operational Concept (HAVOC) by NASA is a mission concept that proposed a crewed aerostat design.


See also

* Geodynamics of Venus * Outline of Venus *
Transit of Venus A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and a inferior and superior planets, superior planet, becoming visible against (and hence obscuring a small portion of) the solar disk. During ...

Transit of Venus
* Venus zone *


Notes


References


External links


Venus profile
at NASA's Solar System Exploration site

an

at the
National Space Science Data CenterThe NASA Space Science Data Coordinated Archive (NSSDCA) serves as the permanent archive for NASA The National Aeronautics and Space Administration (NASA; ) is an independent agencies of the United States government, independent agency of the ...

Soviet Exploration of Venus
an

at Mentallandscape.com



at '' The Nine Planets''
Transits of Venus
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 The United States Geological Survey (USGS, formerly simply Geological Survey) is a scientific agency Agency may refer to: * a governmental or other institution Institutions, according to Samuel P. Huntington, are "stable, valued, recurrin ...

Gazetteer of Planetary Nomenclature: Venus
by the
International Astronomical Union The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a Non-governmental organization, nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting ...

Venus crater database
by the
Lunar and Planetary Institute The Lunar and Planetary Institute (LPI) is a scientific research institute dedicated to study of the Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astron ...

Map of Venus
by
Eötvös Loránd University Eötvös Loránd University ( hu, Eötvös Loránd Tudományegyetem, ELTE) is a Hungarian public university, public research university based in Budapest. Founded in 1635, ELTE is one of the largest and most prestigious public higher education ins ...

Google Venus 3D
interactive map of the planet {{Authority control Astronomical objects known since antiquity Planets of the Solar System Terrestrial planets