Venus

Venus

Overview
Venus is the second planet
Planet
A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...

 from the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

, orbiting it every 224.7 Earth days. The planet is named after Venus
Venus (mythology)
Venus is a Roman goddess principally associated with love, beauty, sex,sexual seduction and fertility, who played a key role in many Roman religious festivals and myths...

, the Roman
Roman mythology
Roman mythology is the body of traditional stories pertaining to ancient Rome's legendary origins and religious system, as represented in the literature and visual arts of the Romans...

 goddess
Goddess
A goddess is a female deity. In some cultures goddesses are associated with Earth, motherhood, love, and the household. In other cultures, goddesses also rule over war, death, and destruction as well as healing....

 of love and beauty. After the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

, it is the brightest natural object in the night sky, reaching an apparent magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...

 of −4.6, bright enough to cast shadows. Because Venus is an inferior planet from Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

, it never appears to venture far from the Sun: its elongation reaches a maximum of 47.8°.
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Encyclopedia
Venus is the second planet
Planet
A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...

 from the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

, orbiting it every 224.7 Earth days. The planet is named after Venus
Venus (mythology)
Venus is a Roman goddess principally associated with love, beauty, sex,sexual seduction and fertility, who played a key role in many Roman religious festivals and myths...

, the Roman
Roman mythology
Roman mythology is the body of traditional stories pertaining to ancient Rome's legendary origins and religious system, as represented in the literature and visual arts of the Romans...

 goddess
Goddess
A goddess is a female deity. In some cultures goddesses are associated with Earth, motherhood, love, and the household. In other cultures, goddesses also rule over war, death, and destruction as well as healing....

 of love and beauty. After the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

, it is the brightest natural object in the night sky, reaching an apparent magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...

 of −4.6, bright enough to cast shadows. Because Venus is an inferior planet from Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

, it never appears to venture far from the Sun: its elongation reaches a maximum of 47.8°. Venus reaches its maximum brightness shortly before sunrise or shortly after sunset, for which reason it has been known as the Morning Star or Evening Star.

Venus is classified as a terrestrial planet
Terrestrial planet
A terrestrial planet, telluric planet or rocky planet is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets are the inner planets closest to the Sun...

 and it is sometimes called Earth's "sister planet" due to the similar size, gravity, and bulk composition. Venus is covered with an opaque layer of highly reflective cloud
Cloud
A cloud is a visible mass of liquid droplets or frozen crystals made of water and/or various chemicals suspended in the atmosphere above the surface of a planetary body. They are also known as aerosols. Clouds in Earth's atmosphere are studied in the cloud physics branch of meteorology...

s of sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...

, preventing its surface from being seen from space in visible light. Venus has the densest atmosphere
Atmosphere
An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...

 of all the terrestrial planets in the Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...

, consisting mostly of carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

. Venus has no carbon cycle
Carbon cycle
The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth...

 to lock carbon back into rocks and surface features, nor does it seem to have any organic life to absorb it in biomass. Venus is believed to have previously possessed Earth-like oceans, but these evaporated as the temperature rose. Venus's surface is a dusty dry desertscape with many slab-like rocks, periodically refreshed by volcanism
Volcanism
Volcanism is the phenomenon connected with volcanoes and volcanic activity. It includes all phenomena resulting from and causing magma within the crust or mantle of a planet to rise through the crust and form volcanic rocks on the surface....

. The water has most likely dissociated
Dissociation (chemistry)
Dissociation in chemistry and biochemistry is a general process in which ionic compounds separate or split into smaller particles, ions, or radicals, usually in a reversible manner...

, and, because of the lack of a planetary magnetic field
Magnetosphere
A magnetosphere is formed when a stream of charged particles, such as the solar wind, interacts with and is deflected by the intrinsic magnetic field of a planet or similar body. Earth is surrounded by a magnetosphere, as are the other planets with intrinsic magnetic fields: Mercury, Jupiter,...

, the hydrogen has been swept into interplanetary space by the solar wind
Solar wind
The solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in temperature and speed over time...

. The atmospheric pressure
Atmospheric pressure
Atmospheric pressure is the force per unit area exerted into a surface by the weight of air above that surface in the atmosphere of Earth . In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point...

 at the planet's surface is 92 times that of the Earth.

The Venusian surface was a subject of speculation until some of its secrets were revealed by planetary science
Planetary science
Planetary science is the scientific study of planets , moons, and planetary systems, in particular those of the Solar System and the processes that form them. It studies objects ranging in size from micrometeoroids to gas giants, aiming to determine their composition, dynamics, formation,...

 in the twentieth century. It was finally mapped in detail by Project Magellan
Magellan probe
The Magellan spacecraft, also referred to as the Venus Radar Mapper, was a 1,035-kilogram robotic space probe launched by NASA on May 4, 1989, to map the surface of Venus using Synthetic Aperture Radar and measure the planetary gravity...

 in 1990–91. The ground shows evidence of extensive volcanism
Volcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...

, and the sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

 in the atmosphere may indicate that there have been some recent eruptions. The absence of evidence of lava
Lava
Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...

 flow accompanying any of the visible caldera
Caldera
A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, such as the one at Yellowstone National Park in the US. They are sometimes confused with volcanic craters...

 remains an enigma. The planet has few impact crater
Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...

s, demonstrating that the surface is relatively young, approximately 300–600 million years old. There is no evidence for plate tectonics
Plate tectonics
Plate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere...

, possibly because its crust is too strong to subduct
Subduction
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...

 without water to make it less viscous. Instead, Venus may lose its internal heat in periodic major resurfacing events.

Physical characteristics


Venus is one of the four solar terrestrial planet
Terrestrial planet
A terrestrial planet, telluric planet or rocky planet is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets are the inner planets closest to the Sun...

s, meaning that, like the Earth, it is a rocky body. In size and mass, it is very similar to the Earth, and is often described as Earth's "sister" or "twin". The diameter of Venus is only 650 km less than the Earth's, and its mass is 81.5% of the Earth's. Conditions on the Venusian surface differ radically from those on Earth, due to its dense carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

 atmosphere
Atmosphere
An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...

. The mass of the atmosphere of Venus is 96.5% carbon dioxide, with most of the remaining 3.5% being nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

.

Internal structure


Without seismic data or knowledge of its moment of inertia
Moment of inertia
In classical mechanics, moment of inertia, also called mass moment of inertia, rotational inertia, polar moment of inertia of mass, or the angular mass, is a measure of an object's resistance to changes to its rotation. It is the inertia of a rotating body with respect to its rotation...

, there is little direct information about the internal structure and geochemistry
Geochemistry
The field of geochemistry involves study of the chemical composition of the Earth and other planets, chemical processes and reactions that govern the composition of rocks, water, and soils, and the cycles of matter and energy that transport the Earth's chemical components in time and space, and...

 of Venus. The similarity in size and density between Venus and Earth suggests that they share a similar internal structure: a core
Planetary core
The planetary core consists of the innermost layer of a planet.The core may be composed of solid and liquid layers, while the cores of Mars and Venus are thought to be completely solid as they lack an internally generated magnetic field. In our solar system, core size can range from about 20% to...

, mantle
Mantle (geology)
The mantle is a part of a terrestrial planet or other rocky body large enough to have differentiation by density. The interior of the Earth, similar to the other terrestrial planets, is chemically divided into layers. The mantle is a highly viscous layer between the crust and the outer core....

, and crust
Crust (geology)
In geology, the crust is the outermost solid shell of a rocky planet or natural satellite, which is chemically distinct from the underlying mantle...

. Like that of Earth, the Venusian core is at least partially liquid because the two planets have been cooling at about the same rate. The slightly smaller size of Venus suggests that pressures are significantly lower in its deep interior than Earth. The principal difference between the two planets is the lack of plate tectonics
Plate tectonics
Plate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere...

 on Venus, likely due to the dry surface and mantle. 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
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...

.

Geography


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
Ishtar Terra is one of two main highland regions on the planet Venus. It is the smaller of the two "continents", and is located near the north pole. It is named after the Akkadian goddess Ishtar....

, after Ishtar
Ishtar
Ishtar is the Assyrian and Babylonian goddess of fertility, love, war, and sex. She is the counterpart to the Sumerian Inanna and to the cognate north-west Semitic goddess Astarte.-Characteristics:...

, the Babylon
Babylon
Babylon was an Akkadian city-state of ancient Mesopotamia, the remains of which are found in present-day Al Hillah, Babil Province, Iraq, about 85 kilometers south of Baghdad...

ian goddess of love, and is about the size of Australia. Maxwell Montes
Maxwell Montes
Maxwell Montes is a mountain massif on the planet Venus, part of which contains the highest point on the planet's surface.- General description :...

, the highest mountain on Venus, lies on Ishtar Terra. Its peak is 11 km above the Venusian average surface elevation. The southern continent is called Aphrodite Terra
Aphrodite Terra
Aphrodite Terra is a highland region on Venus, near the equator. It is about the same size as Africa, and much rougher than Ishtar Terra.The surface appears buckled and fractured which suggests large compressive forces. There are also numerous extensive lava flows. Channels cross this terrain and...

, after the Greek
Greek mythology
Greek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...

 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.
As well as the impact crater
Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...

s, mountains, and valleys commonly found on rocky planets, Venus has a number of unique surface features. Among these are flat-topped volcanic features called farra, which look somewhat like pancakes and range in size from 20–50 km across, and 100–1,000 m high; radial, star-like fracture systems called novae; features with both radial and concentric fractures resembling spider webs, known as arachnoids
Arachnoid (astrogeology)
In astrogeology, an arachnoid is a large structure of unknown origin, and they have been found only on the surface of the planet Venus. Arachnoids get their name from their resemblance to spider webs. They appear as concentric ovals surrounded by a complex network of fractures, and can span 200...

; 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
James Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory...

, and highland regions Alpha Regio
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 Dick Goldstein in 1964. The name was approved by the International Astronomical Union's Working Group for Planetary System Nomenclature between 1976 and 1979...

, Beta Regio
Beta Regio
Beta Regio is a region of the planet Venus known as a volcanic rise. Measuring about 3000 km, it constitutes a prominent upland region of Venus centered at ....

 and Ovda Regio
Ovda Regio
Ovda Regio is a region on Venus that forms the western part of Aphrodite Terra. Magellan images show a complex surface, with several generations of structures. A pervasive fabric of irregular broad domes and ridges and associated curvilinear valleys was flooded by lava, then fractured...

. The former three features were named before the current system was adopted by the International Astronomical Union
International Astronomical Union
The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...

, the body that oversees planetary nomenclature.

The longitudes of physical features on Venus are expressed relative to its prime meridian
Prime Meridian
The Prime Meridian is the meridian at which the longitude is defined to be 0°.The Prime Meridian and its opposite the 180th meridian , which the International Date Line generally follows, form a great circle that divides the Earth into the Eastern and Western Hemispheres.An international...

. The original prime meridian passed through the radar-bright spot at the center 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.

Surface geology




Much of the Venusian surface appears to have been shaped by volcanic activity. Venus has several times as many volcanoes as Earth, and it possesses some 167 large volcanoes that are over 100 km across. The only volcanic complex of this size on Earth is the Big Island
Hawaii (island)
The Island of Hawaii, also called the Big Island or Hawaii Island , is a volcanic island in the North Pacific Ocean...

 of Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

. This is not because Venus is more volcanically active than Earth, but because its crust is older. Earth's oceanic crust
Oceanic crust
Oceanic crust is the part of Earth's lithosphere that surfaces in the ocean basins. Oceanic crust is primarily composed of mafic rocks, or sima, which is rich in iron and magnesium...

 is continually recycled by subduction
Subduction
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...

 at the boundaries of tectonic plates, and has an average age of about 100 million years, while the Venusian surface is estimated to be 300–600 million years old.

Several lines of evidence point to ongoing volcanic
Volcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...

 activity on Venus. During the Soviet Venera
Venera
The Venera series probes were developed by the Soviet Union between 1961 and 1984 to gather data from Venus, Venera being the Russian name for Venus...

 program, the Venera 11
Venera 11
The Venera 11 was a USSR unmanned space mission part of the Venera program to explore the planet Venus. Venera 11 was launched on 9 September 1978 at 3:25:39 UTC....

 and Venera 12
Venera 12
The Venera 12 was an USSR unmanned space mission to explore the planet Venus. Venera 12 was launched on 14 September 1978 at 02:25:13 UTC. Separating from its flight platform on December 19, 1978, the lander entered the Venus atmosphere two days later at 11.2 km/s. During the descent, it...

 probes detected a constant stream of lightning
Lightning
Lightning is an atmospheric electrostatic discharge accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...

, and Venera 12 recorded a powerful clap of thunder
Thunder
Thunder is the sound made by lightning. Depending on the nature of the lightning and distance of the listener, thunder can range from a sharp, loud crack to a long, low rumble . The sudden increase in pressure and temperature from lightning produces rapid expansion of the air surrounding and within...

 soon after it landed. The European Space Agency's Venus Express
Venus Express
Venus Express is the first Venus exploration mission of the European Space Agency. Launched in November 2005, it arrived at Venus in April 2006 and has been continuously sending back science data from its polar orbit around Venus. Equipped with seven science instruments, the main objective of the...

 recorded abundant lightning in the high atmosphere. While rainfall drives thunderstorm
Thunderstorm
A thunderstorm, also known as an electrical storm, a lightning storm, thundershower or simply a storm is a form of weather characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere known as thunder. The meteorologically assigned cloud type associated with the...

s on Earth, there is no rainfall on the surface of Venus (though it does rain sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...

 in the upper atmosphere that evaporates around 25 km above the surface). One possibility is that ash from a volcanic eruption was generating the lightning. Another piece of evidence comes from measurements of sulfur dioxide concentrations in the atmosphere, which were found to drop by a factor of 10 between 1978 and 1986. This may imply that the levels had earlier been boosted by a large volcanic eruption.

There are almost a thousand impact craters on Venus evenly distributed across its surface. On other cratered bodies, such as the Earth and the Moon, craters show a range of states of degradation. On the Moon, degradation is caused by subsequent impacts, while on Earth, it is caused by wind and rain erosion. On Venus, about 85% of craters are in pristine condition. The number of craters, together with their well-preserved condition, indicates that the planet underwent a global resurfacing event about 300–600 million years ago, followed by a decay in volcanism. Earth's crust is in continuous motion, but it is thought that Venus cannot 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 100 million years, subduction occurs on an enormous scale, completely recycling the crust.

Venusian craters range from 3 km to 280 km in diameter. There are no craters smaller than 3 km, because of the effects of the dense atmosphere on incoming objects. Objects with less than a certain kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...

 are slowed down so much by the atmosphere that they do not create an impact crater. Incoming projectiles less than 50 meters in diameter will fragment and burn up in the atmosphere before reaching the ground.

Atmosphere and climate




Venus has an extremely dense atmosphere, which consists mainly of carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

 and a small amount of nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

. The atmospheric mass is 93 times that of Earth's atmosphere while the pressure at the planet's surface is about 92 times that at Earth's surface—a pressure equivalent to that at a depth of nearly 1 kilometer under Earth's ocean
Ocean
An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...

s. The density at the surface is 65 kg/m³ (6.5% that of water). The CO2-rich atmosphere, along with thick clouds of sulfur dioxide
Sulfur dioxide
Sulfur dioxide is the chemical compound with the formula . It is released by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide unless the sulfur compounds are removed before burning the fuel...

, generates the strongest greenhouse effect
Greenhouse effect
The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions. Since part of this re-radiation is back towards the surface, energy is transferred to the surface and the lower atmosphere...

 in the Solar System, creating surface temperatures of over 460 °C (860 °F). This makes the Venusian surface hotter than Mercury
Mercury (planet)
Mercury is the innermost and smallest planet in the Solar System, orbiting the Sun once every 87.969 Earth days. The orbit of Mercury has the highest eccentricity of all the Solar System planets, and it has the smallest axial tilt. It completes three rotations about its axis for every two orbits...

's which has a minimum surface temperature of −220 °C and maximum surface temperature of 420 °C, even though Venus is nearly twice Mercury's distance from the Sun and thus receives only 25% of Mercury's solar irradiance
Irradiance
Irradiance is the power of electromagnetic radiation per unit area incident on a surface. Radiant emittance or radiant exitance is the power per unit area radiated by a surface. The SI units for all of these quantities are watts per square meter , while the cgs units are ergs per square centimeter...

. The surface of Venus is often said to resemble Hell
Hell
In many religious traditions, a hell is a place of suffering and punishment in the afterlife. Religions with a linear divine history often depict hells as endless. Religions with a cyclic history often depict a hell as an intermediary period between incarnations...

.

Studies have suggested that several billion years ago the Venusian atmosphere was much more like Earth's than it is now, and that there were probably substantial quantities of liquid water on the surface, but a runaway greenhouse effect
Runaway greenhouse effect
A runaway greenhouse effect is not a clearly defined term, but is understood to mean an event analogous to that which is believed to have happened in the early history of Venus, where positive feedback increased the strength of its greenhouse effect until its oceans boiled away...

 was caused by the evaporation of that original water, which generated a critical level of greenhouse gases in its atmosphere.

Thermal inertia and the transfer of heat by winds in the lower atmosphere mean that the temperature of the Venusian surface does not vary significantly between the night and day sides, despite the planet's extremely slow rotation. Winds at the surface are slow, moving at a few kilometers per hour, but because of the high density of the atmosphere at the Venusian 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 if the heat and lack of oxygen were not a problem.

Above the dense CO2 layer are thick clouds consisting mainly of sulfur dioxide
Sulfur dioxide
Sulfur dioxide is the chemical compound with the formula . It is released by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide unless the sulfur compounds are removed before burning the fuel...

 and sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...

 droplets. These clouds reflect about 60% of the sunlight that falls on them back into space, and prevent the direct observation of the Venusian surface in visible light. The permanent cloud cover means that although Venus is closer than Earth to the Sun, the Venusian surface is not as well lit. Strong 300 km/h winds at the cloud tops circle the planet about every four to five earth days. Venusian winds move at up to 60 times the speed of the planet's rotation, while Earth's fastest winds are only 10% to 20% rotation speed.

The surface of Venus is effectively isothermal; it retains a constant temperature not only between day and night but between the equator and the poles. The planet's minute axial tilt
Axial tilt
In astronomy, axial tilt is the angle between an object's rotational axis, and a line perpendicular to its orbital plane...

 (less than three degrees, compared with 23 degrees for Earth), also minimizes season
Season
A season is a division of the year, marked by changes in weather, ecology, and hours of daylight.Seasons result from the yearly revolution of the Earth around the Sun and the tilt of the Earth's axis relative to the plane of revolution...

al temperature variation. The only appreciable variation in temperature occurs with altitude. In 1995, the Magellan probe
Magellan probe
The Magellan spacecraft, also referred to as the Venus Radar Mapper, was a 1,035-kilogram robotic space probe launched by NASA on May 4, 1989, to map the surface of Venus using Synthetic Aperture Radar and measure the planetary gravity...

 imaged a highly reflective substance
Venus snow
The Venus snow is a brightening of the radar reflection from the surface of Venus at high elevations. The nature of the "snow" was initially unknown. It could not be water ice, which cannot exist in the extremely hot, dry conditions of the Venusian surface...

 at the tops of the highest mountain peaks which bore a strong resemblance to terrestrial snow
Snow
Snow is a form of precipitation within the Earth's atmosphere in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. Since snow is composed of small ice particles, it is a granular material. It has an open and therefore soft structure, unless packed by...

. This substance arguably formed from a similar process to snow, albeit at a far higher temperature. Too volatile to condense on the surface, it rose in gas form to cooler higher elevations, where it then fell as precipitation. The identity of this substance is not known with certainty, but speculation has ranged from elemental tellurium to lead sulfide (galena
Galena
Galena is the natural mineral form of lead sulfide. It is the most important lead ore mineral.Galena is one of the most abundant and widely distributed sulfide minerals. It crystallizes in the cubic crystal system often showing octahedral forms...

).

The clouds of Venus are capable of producing lightning
Lightning
Lightning is an atmospheric electrostatic discharge accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...

 much like the clouds on Earth. The existence of lightning had been controversial since the first suspected bursts were detected by the Soviet Venera probe
Venera
The Venera series probes were developed by the Soviet Union between 1961 and 1984 to gather data from Venus, Venera being the Russian name for Venus...

s. In 2006–07 Venus Express
Venus Express
Venus Express is the first Venus exploration mission of the European Space Agency. Launched in November 2005, it arrived at Venus in April 2006 and has been continuously sending back science data from its polar orbit around Venus. Equipped with seven science instruments, the main objective of the...

 clearly detected whistler mode wave
Electromagnetic electron wave
An electromagnetic electron wave is a wave in a plasma which has a magnetic field component and in which primarily the electrons oscillate.In an unmagnetized plasma, an electromagnetic electron wave is simply a light wave modified by the plasma...

s, the signatures of lightning. Their intermittent appearance indicates a pattern associated with weather activity. The lightning rate is at least half of that on Earth. In 2007 the Venus Express probe discovered that a huge double atmospheric vortex
Polar vortex
A polar vortex is a persistent, large-scale cyclone located near one or both of a planet's geographical poles. On Earth, the polar vortices are located in the middle and upper troposphere and the stratosphere...

 exists at the south pole of the planet.

Magnetic field and core



In 1967, Venera-4 found that the Venusian magnetic field
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...

 is much weaker than that of Earth. This magnetic field is induced by an interaction between the ionosphere
Ionosphere
The ionosphere is a part of the upper atmosphere, comprising portions of the mesosphere, thermosphere and exosphere, distinguished because it is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere...

 and the solar wind
Solar wind
The solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in temperature and speed over time...

, rather than by an internal dynamo
Dynamo theory
In geophysics, dynamo theory proposes a mechanism by which a celestial body such as the Earth or a star generates a magnetic field. The theory describes the process through which a rotating, convecting, and electrically conducting fluid can maintain a magnetic field over astronomical time...

 in the core
Planetary core
The planetary core consists of the innermost layer of a planet.The core may be composed of solid and liquid layers, while the cores of Mars and Venus are thought to be completely solid as they lack an internally generated magnetic field. In our solar system, core size can range from about 20% to...

 like the one inside the Earth. Venus' small induced magnetosphere provides negligible protection to the atmosphere against cosmic radiation. This radiation may result in cloud-to-cloud lightning discharges.

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
Electrical conductor
In physics and electrical engineering, a conductor is a material which contains movable electric charges. In metallic conductors such as copper or aluminum, the movable charged particles are electrons...

 liquid, rotation, and convection
Convection
Convection is the movement of molecules within fluids and rheids. It cannot take place in solids, since neither bulk current flows nor significant diffusion can take place in solids....

. The core is thought to be electrically conductive and, while its rotation is often thought to be too slow, simulations show that it is adequate to produce a dynamo. This implies that the dynamo is missing because of a lack of convection in the Venusian core. On Earth, convection occurs in the liquid outer layer of the core because the bottom of the liquid layer is much hotter than the top. On Venus, a global resurfacing event may have shut down plate tectonics and led to a reduced heat flux through the crust. This caused the mantle temperature to increase, thereby reducing the heat flux out of the core. As a result, there is not an internal geodynamo that can drive a magnetic field. Instead the heat energy from the core is being used to reheat the crust.

One possibility is that Venus has no solid inner core, or its core is not currently 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
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

, which is unknown at present.

Orbit and rotation


Venus orbits the Sun at an average distance of about 108 million kilometers (about 0.7 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....

), and completes an orbit every 224.65 days. Although all planetary orbit
Planetary orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...

s are elliptical
Ellipse
In geometry, an ellipse is a plane curve that results from the intersection of a cone by a plane in a way that produces a closed curve. Circles are special cases of ellipses, obtained when the cutting plane is orthogonal to the cone's axis...

, Venus is the closest to circular
Circle
A circle is a simple shape of Euclidean geometry consisting of those points in a plane that are a given distance from a given point, the centre. The distance between any of the points and the centre is called the radius....

, with an eccentricity of less than 0.01. When Venus lies between the Earth and the Sun, a position known as "inferior conjunction", it makes the closest approach to Earth of any planet, lying at an average distance of 41 million km during inferior conjunction. The planet reaches inferior conjunction every 584 days, on average. Due to the decreasing eccentricity of Earth, the minimum distances will become greater. From the year 1 to 5383, there are 526 approaches less than 40 million km; then there are none for about 60,200 years. During periods of greater eccentricity Venus can come as close as 38.2 million km.

All the planets of the Solar System orbit in a counter-clockwise direction as viewed from above the Sun's north pole: most planets also rotate counter-clockwise but Venus rotates clockwise (called "retrograde"
Retrograde motion
Retrograde motion is motion in the direction opposite to the movement of something else, and is the contrary of direct or prograde motion. This motion can be the orbit of one body about another body or about some other point, or the rotation of a single body about its axis, or other phenomena such...

 rotation) once every 243 Earth days—by far the slowest rotation period of any major planet. The equator of the Venusian surface rotates at 6.5 km/h while on Earth rotation speed at the equator is about 1,670 km/h. A Venusian sidereal day thus lasts longer than a Venusian year (243 versus 224.7 Earth days). Because of the retrograde rotation the length of a solar day on Venus is significantly shorter than the sidereal day. As a result of Venus's relatively long solar day, one Venusian year is about 1.92 Venusian days long. To an observer on the surface of Venus the Sun would appear to rise in the west and set in the east and the time from one sunrise to the next would be 116.75 Earth days (making the Venusian solar day shorter than Mercury's
Mercury (planet)
Mercury is the innermost and smallest planet in the Solar System, orbiting the Sun once every 87.969 Earth days. The orbit of Mercury has the highest eccentricity of all the Solar System planets, and it has the smallest axial tilt. It completes three rotations about its axis for every two orbits...

 176 Earth days).

Venus may have formed from the solar nebula
Solar nebula
In cosmogony, the nebular hypothesis is the most widely accepted model explaining the formation and evolution of the Solar System. There is evidence that it was first proposed in 1734 by Emanuel Swedenborg. Originally applied only to our own Solar System, this method of planetary system formation...

 with a different rotation period and obliquity, reaching to its current state because of chaotic spin changes caused by planetary perturbations and tidal
Tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....

 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.
A curious aspect of the Venusian orbit and rotation periods is that the 584-day average interval between successive close approaches to the Earth is almost exactly equal to five Venusian solar days. Whether this relationship arose by chance or is the result of tidal locking
Tidal locking
Tidal locking occurs when the gravitational gradient makes one side of an astronomical body always face another; for example, the same side of the Earth's Moon always faces the Earth. A tidally locked body takes just as long to rotate around its own axis as it does to revolve around its partner...

 with the Earth is unknown.

Venus currently has no natural satellite, though the asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...

 2002 VE68
2002 VE68
' is a quasi-satellite of Venus. It was discovered on November 11, 2002.This asteroid is also a Mercury grazer and an Earth crosser; it seems to have been co-orbital with Venus for only the last 7000 years, and is destined to be ejected from this orbital arrangement about 500 years from now...

 presently maintains a quasi-orbital
Quasi-satellite
A quasi-satellite is an object in a 1:1 orbital resonance with its planet that stays close to the planet over many orbital periods.A quasi-satellite's orbit around the Sun takes exactly the same time as the planet's, but has a different eccentricity , as shown in the diagram on the right...

 relationship with it. In the 17th century Giovanni Cassini
Giovanni Domenico Cassini
This article is about the Italian-born astronomer. For his French-born great-grandson, see Jean-Dominique Cassini.Giovanni Domenico Cassini was an Italian/French mathematician, astronomer, engineer, and astrologer...

 reported a moon orbiting Venus which was named Neith
Neith (hypothetical moon)
Neith is the name given to an object first sighted by Giovanni Cassini, which he believed to be a moon of Venus. It has since been determined that no such moon exists.In 1672, Giovanni Cassini found a small object close to Venus...

 and there were numerous reported sightings over the following 200 years but it was ultimately determined that most were stars in the vicinity. Alex Alemi's and David Stevenson
David J. Stevenson
David John Stevenson is a professor of planetary science at Caltech. Originally from New Zealand, he received his Ph.D. from Cornell University in physics, where he proposed a model for the interior of Jupiter. He is well-known for applying fluid mechanics and magnetohydrodynamics to understand...

's 2006 study of models of the early Solar System at the California Institute of Technology
California Institute of Technology
The California Institute of Technology is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering...

 shows that it is likely that billions of years ago Venus had at least one moon created by a huge impact event
Impact event
An impact event is the collision of a large meteorite, asteroid, comet, or other celestial object with the Earth or another planet. Throughout recorded history, hundreds of minor impact events have been reported, with some occurrences causing deaths, injuries, property damage or other significant...

. About 10 million years 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 and merged with Venus. If later impacts created moons these also were absorbed 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.

Observation



Venus is always brighter than any star. The greatest luminosity, apparent magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...

 −4.9, occurs during crescent phase when it is near the Earth. Venus fades to about magnitude -3 when it is backlit by the Sun. The planet is bright enough to be seen in the middle of the day when the sky is very clear, and the planet can be easy to see when the Sun is low on the horizon. As an inferior planet, it always lies within about 47° of the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

.

Venus "overtakes" the 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. While Mercury
Mercury (planet)
Mercury is the innermost and smallest planet in the Solar System, orbiting the Sun once every 87.969 Earth days. The orbit of Mercury has the highest eccentricity of all the Solar System planets, and it has the smallest axial tilt. It completes three rotations about its axis for every two orbits...

, 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
Unidentified flying object
A term originally coined by the military, an unidentified flying object is an unusual apparent anomaly in the sky that is not readily identifiable to the observer as any known object...

". U.S. President Jimmy Carter
Jimmy Carter
James Earl "Jimmy" Carter, Jr. is an American politician who served as the 39th President of the United States and was the recipient of the 2002 Nobel Peace Prize, the only U.S. President to have received the Prize after leaving office...

 reported having seen a UFO
Jimmy Carter UFO incident
The Jimmy Carter UFO Incident is the name given to an incident in which Jimmy Carter reported seeing an unidentified flying object while at Leary, Georgia in 1969....

 in 1969, which later analysis suggested was probably the planet. Countless other people have mistaken Venus for something more exotic.


As it moves around its orbit, Venus displays phases
Planetary phase
Planetary phase is the term used to describe the appearance of the illuminated section of a planet. Like lunar phases, the planetary phase depends on the relative position of the sun, the planet and the observer....

 in a telescopic
Optical telescope
An optical telescope is a telescope which is used to gather and focus light mainly from the visible part of the electromagnetic spectrum for directly viewing a magnified image for making a photograph, or collecting data through electronic image sensors....

 view like those of the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

: In the phases of Venus
Phases of Venus
The phases of the planet Venus are the different variations of lighting seen on the planet's surface, similar to lunar phases. The first recorded observations of them were telescopic observations by Galileo Galilei in 1610...

 the planet presents a small "full" image when it is on the opposite side of the Sun. It shows a larger "quarter phase" when it is at its maximum elongations from the Sun. Venus is at its brightest in the night sky and presents a much larger "thin crescent" in telescopic views as it comes around to the near side between the Earth and the Sun. Venus is at its largest and presents its "new phase" when it is between the Earth and the Sun. Since it has an atmosphere it can be seen in a telescope by the halo of light refracted around the planet.

The Venusian orbit is slightly inclined relative to the Earth's orbit; thus, when the planet passes between the Earth and the Sun, it usually does not cross the face of the Sun. Transits of Venus do occur when the planet's inferior conjunction coincides with its presence in the plane of the Earth's orbit. Transits of Venus occur in cycles of 243 years with the current pattern of transits being pairs of transits separated by eight years, at intervals of about 105.5 years or 121.5 years. The most recent transit
Transit of Venus, 2004
The most recent transit of Venus when observed from Earth took place on June 8, 2004. The event received significant attention, since it was the first Venus transit to take place after the invention of broadcast media...

 was in June 2004; the next will be in June 2012. The preceding pair of transits occurred in December 1874 and December 1882; the following pair will occur in December 2117 and December 2125. Historically, transits of Venus were important, because they allowed astronomers to directly determine the size of the astronomical unit
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....

, and hence the size of the Solar System. Captain Cook's exploration of the east coast of Australia came after he had sailed to Tahiti
Tahiti
Tahiti is the largest island in the Windward group of French Polynesia, located in the archipelago of the Society Islands in the southern Pacific Ocean. It is the economic, cultural and political centre of French Polynesia. The island was formed from volcanic activity and is high and mountainous...

 in 1768 to observe a transit of Venus.

A long-standing mystery of Venus observations is the so-called Ashen light
Ashen light
Ashen light is a subtle glow that is seen from the night side of the planet Venus. This ashen light is said to be very similar to Earthshine on our moon, but not as distinguished in brightness. It was first sighted by the astronomer Giovanni Battista Riccioli on January 9, 1643, and has been...

—an apparent weak illumination of the dark side of the planet, seen when the planet is in the crescent phase. The first claimed observation of ashen light was made as long ago as 1643, but the existence of the illumination has never been reliably confirmed. Observers have speculated that it may result from electrical activity in the Venusian atmosphere, but it may be illusory, resulting from the physiological effect of observing a very bright crescent-shaped object.

Early studies


Venus was known to ancient civilizations both as the "morning star" and as the "evening star", names that reflect the early understanding that these were two separate objects. The Venus tablet of Ammisaduqa
Venus tablet of Ammisaduqa
The Venus tablet of Ammisaduqa refers to the record of astronomical observations of Venus, as preserved in numerous cuneiform tablets dating from the first millennium BCE. It is believed that this astronomical record was first compiled during the reign of King Ammisaduqa , the fourth ruler after...

, dated 1581 BC, shows that the Babylonians understood that the two were a single object, referred to in the tablet as the "bright queen of the sky," and could support this view with detailed observations. The Greeks thought of the two as separate stars, Phosphorus
Phosphorus (morning star)
Phosphorus , a name meaning "Light-Bringer", is the Morning Star, the planet Venus in its morning appearance. Φαοσφόρος and Φαεσφόρος are forms of the same name in some Greek dialects....

 and Hesperus
Hesperus
In Greek mythology, Hesperus is the Evening Star, the planet Venus in the evening. He is the son of the dawn goddess Eos and is the brother of Eosphorus , the Morning Star. Hesperus' Roman equivalent is Vesper...

, until the time of Pythagoras
Pythagoras
Pythagoras of Samos was an Ionian Greek philosopher, mathematician, and founder of the religious movement called Pythagoreanism. Most of the information about Pythagoras was written down centuries after he lived, so very little reliable information is known about him...

 in the sixth century BC.
The Romans designated the morning aspect of Venus as Lucifer
Lucifer
Traditionally, Lucifer is a name that in English generally refers to the devil or Satan before being cast from Heaven, although this is not the original meaning of the term. In Latin, from which the English word is derived, Lucifer means "light-bearer"...

, literally "Light-Bringer", and the evening aspect as Vesper
Vesper
Vesper means evening in Classical Latin. It can refer to:*Hesperus, Latinized form of Hesperos, a Greek mythological figure Places:*Vesper, Wisconsin, a village*Vesper Peak, a mountain in Washington State...

.

The transit of Venus
Transit of Venus
A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and Earth, becoming visible against the solar disk. During a transit, Venus can be seen from Earth as a small black disk moving across the face of the Sun...

 was first observed in 1032 by the Persian astronomer Avicenna
Avicenna
Abū ʿAlī al-Ḥusayn ibn ʿAbd Allāh ibn Sīnā , commonly known as Ibn Sīnā or by his Latinized name Avicenna, was a Persian polymath, who wrote almost 450 treatises on a wide range of subjects, of which around 240 have survived...

, who concluded that Venus is closer to the Earth than the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

, and established that Venus was, at least sometimes, below the Sun. In the 12th century, the Andalusian
Al-Andalus
Al-Andalus was the Arabic name given to a nation and territorial region also commonly referred to as Moorish Iberia. The name describes parts of the Iberian Peninsula and Septimania governed by Muslims , at various times in the period between 711 and 1492, although the territorial boundaries...

 astronomer Ibn Bajjah
Ibn Bajjah
Abū-Bakr Muhammad ibn Yahya ibn al-Sāyigh , known as Ibn Bājjah , was an Andalusian polymath: an astronomer, logician, musician, philosopher, physician, physicist, psychologist, botanist, poet and scientist. He was known in the West by his Latinized name, Avempace...

 observed "two planets as black spots on the face of the Sun," which was later identified as the transit of Venus
Transit of Venus
A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and Earth, becoming visible against the solar disk. During a transit, Venus can be seen from Earth as a small black disk moving across the face of the Sun...

 and Mercury by the Maragha
Maragheh observatory
Maragheh observatory is an astronomical observatory which was established in 1259 CE by Nasir al-Din al-Tusi, an Iranian scientist and astronomer...

 astronomer Qotb al-Din Shirazi in the 13th century.

When the Italian physicist Galileo Galilei
Galileo Galilei
Galileo Galilei , was an Italian physicist, mathematician, astronomer, and philosopher who played a major role in the Scientific Revolution. His achievements include improvements to the telescope and consequent astronomical observations and support for Copernicanism...

 first observed the planet in the early 17th century, he found that it showed phases
Planetary phase
Planetary phase is the term used to describe the appearance of the illuminated section of a planet. Like lunar phases, the planetary phase depends on the relative position of the sun, the planet and the observer....

 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
Ptolemy
Claudius Ptolemy , was a Roman citizen of Egypt who wrote in Greek. He was a mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology. He lived in Egypt under Roman rule, and is believed to have been born in the town of Ptolemais Hermiou in the...

 geocentric model
Geocentric model
In astronomy, the geocentric model , is the superseded theory that the Earth is the center of the universe, and that all other objects orbit around it. This geocentric model served as the predominant cosmological system in many ancient civilizations such as ancient Greece...

 that the Solar System was concentric and centered on the Earth.

The atmosphere of Venus
Atmosphere of Venus
The atmosphere of Venus is much denser and hotter than that of Earth. The temperature at the surface is 740 K , while the pressure is 93 bar. The Venusian atmosphere supports opaque clouds made of sulfuric acid, making optical Earth-based and orbital observation of the surface impossible...

 was discovered in 1761 by Russian polymath Mikhail Lomonosov
Mikhail Lomonosov
Mikhail Vasilyevich Lomonosov was a Russian polymath, scientist and writer, who made important contributions to literature, education, and science. Among his discoveries was the atmosphere of Venus. His spheres of science were natural science, chemistry, physics, mineralogy, history, art,...

. Venus' atmosphere was observed in 1790 by German astronomer Johann Schröter. Schröter found that when the planet was a thin crescent, the cusps extended through more than 180°. He correctly surmised that this was due to scattering
Scattering
Scattering is a general physical process where some forms of radiation, such as light, sound, or moving particles, are forced to deviate from a straight trajectory by one or more localized non-uniformities in the medium through which they pass. In conventional use, this also includes deviation of...

 of sunlight in a dense atmosphere. Later, American astronomer Chester Smith Lyman observed a complete ring around the dark side of the planet when it was at inferior conjunction, 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 and Schröter incorrectly estimated periods of about 24 hours 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
Astronomical spectroscopy
Astronomical spectroscopy is the technique of spectroscopy used in astronomy. The object of study is the spectrum of electromagnetic radiation, including visible light, which radiates from stars and other celestial objects...

, radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

 and ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...

 observations that more of its secrets were revealed. The first UV observations were carried out in the 1920s, when Frank E. Ross found that UV photographs revealed considerable detail that was absent in visible and infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...

 radiation. He suggested that this was due to a very dense yellow lower atmosphere with high cirrus cloud
Cirrus cloud
Cirrus clouds are atmospheric clouds generally characterized by thin, wispy strands, giving them their name from the Latin word cirrus meaning a ringlet or curling lock of hair...

s above it.

Spectroscopic observations in the 1900s gave the first clues about the Venusian rotation. Vesto Slipher
Vesto Slipher
Vesto Melvin Slipher was an American astronomer. His brother Earl C. Slipher was also an astronomer and a director at the Lowell Observatory....

 tried to measure the Doppler shift of light from Venus, but found that he could not detect any rotation. He surmised that the planet must have a much longer rotation period than had previously been thought. Later work in the 1950s showed that 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 300 m radio telescope at Arecibo Observatory
Arecibo Observatory
The Arecibo Observatory is a radio telescope near the city of Arecibo in Puerto Rico. It is operated by SRI International under cooperative agreement with the National Science Foundation...

, and the echoes revealed two highly reflective regions, designated the Alpha and Beta regions. The observations also revealed a bright region attributed to mountains, which was called Maxwell Montes. These three features are now the only ones on Venus which do not have female names.

Early efforts



The first robotic
Robotic spacecraft
A robotic spacecraft is a spacecraft with no humans on board, that is usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather than crewed operation, due to...

 space probe
Space probe
A robotic spacecraft is a spacecraft with no humans on board, that is usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather than crewed operation, due to...

 mission to Venus, and the first to any planet, began on February 12, 1961 with the launch of the Venera 1
Venera 1
On February 12, 1961, 00:34:36 UTC, was the first planetary probe launched to Venus by the Soviet Union. The Venus-1 Automatic Interplanetary Station, or Venera 1, was a 643.5 kg probe consisting of a cylindrical body 1.05 metres in diameter topped by a dome, totalling 2.035 metres...

 probe. The first craft of the otherwise highly successful Soviet Venera program, Venera 1 was launched on a direct impact trajectory, but contact was lost seven days into the mission, when the probe was about 2 million km from Earth. It was estimated to have passed within 100,000 km from Venus in mid-May.

The United States exploration of Venus also started badly with the loss of the Mariner 1
Mariner 1
Mariner 1 was the first spacecraft of the American Mariner program. Launched on July 22, 1962 as a Venus flyby mission, a range safety officer ordered its destructive abort at 09:26:16 UT, 294.5 seconds after launch....

 probe on launch. The subsequent Mariner 2
Mariner 2
Mariner 2 , an American space probe to Venus, was the first space probe to conduct a successful planetary encounter . The first successful spacecraft in the NASA Mariner program, it was a simplified version of the Block I spacecraft of the Ranger program and an exact copy of Mariner 1...

 mission enjoyed greater success, and after a 109-day transfer orbit on December 14, 1962 it became the world's first successful interplanetary mission, passing 34,833 km above the surface of Venus. Its microwave
Microwave
Microwaves, a subset of radio waves, have wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz and 300 GHz. This broad definition includes both UHF and EHF , and various sources use different boundaries...

 and infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...

 radiometer
Radiometer
A radiometer is a device for measuring the radiant flux of electromagnetic radiation. Generally, the term radiometer denotes an infrared radiation detector, yet it also includes detectors operating on any electromagnetic wavelength....

s revealed that while the Venusian cloud tops were cool, the surface was extremely hot—at least 425 °C, finally ending any hopes that the planet might harbor ground-based life. Mariner 2 also obtained improved estimates of its mass and of the astronomical unit
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....

, but was unable to detect either a magnetic field
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...

 or radiation belts.

Atmospheric entry


The Soviet Venera 3
Venera 3
Venera 3 was a Venera program space probe that was built and launched by the Soviet Union to explore the surface of Venus. It was launched on November 16, 1965 at 04:19 UTC from Baikonur, Kazakhstan....

 probe crash-landed on Venus on March 1, 1966. It was the first man-made object to enter the atmosphere and strike the surface of another planet, though its communication system failed before it was able to return any planetary data. Venus's next encounter with an unmanned probe came on October 18, 1967 when Venera 4
Venera 4
Venera 4 ) was a probe in the Soviet Venera program for the exploration of Venus. Venera-4 was the first successful probe to perform in-place analysis of the environment of another planet. It was also the first probe to land on another planet...

 successfully entered the atmosphere and deployed a number of science experiments. Venera 4 showed that the surface temperature was even hotter than Mariner 2 had measured at almost 500 °C, and that the atmosphere was about 90 to 95% carbon dioxide. The Venusian atmosphere was considerably denser than Venera 4's designers had anticipated, and its slower than intended parachute descent meant that its batteries ran down before the probe reached the surface. After returning descent data for 93 minutes, Venera 4's last pressure reading was 18 bar
Bar (unit)
The bar is a unit of pressure equal to 100 kilopascals, and roughly equal to the atmospheric pressure on Earth at sea level. Other units derived from the bar are the megabar , kilobar , decibar , centibar , and millibar...

 at an altitude of 24.96 km.

Another probe arrived at Venus one day later on October 19, 1967 when Mariner 5
Mariner 5
Mariner 5 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 spectrum, and sample the solar particles and magnetic field fluctuations above the planet...

 conducted a flyby at a distance of less than 4000 km above the cloud tops. Mariner 5 was originally built as backup for the Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...

-bound Mariner 4
Mariner 4
Mariner 4 was the fourth in a series of spacecraft, launched on November 28, 1964, intended for planetary exploration in a flyby mode and performed the first successful flyby of the planet Mars, returning the first pictures of the Martian surface...

, but when that mission was successful, the probe was refitted for a Venus mission. A suite of instruments more sensitive than those on Mariner 2, in particular its radio occultation
Radio occultation
Radio occultation is a remote sensing technique used for measuring the physical properties of a planetary atmosphere. It relies on the detection of a change in a radio signal as it passes through the planet's atmosphere i.e. as it is occulted by the atmosphere. When electromagnetic radiation...

 experiment, returned data on the composition, pressure and density of the Venusian atmosphere. The joint Venera 4–Mariner 5 data were analyzed by a combined Soviet-American science team in a series of colloquia over the following year, in an early example of space cooperation.

Armed with the lessons and data learned from Venera 4, the Soviet Union launched the twin probes Venera 5
Venera 5
Venera 5 was a probe in the Soviet space program Venera for the exploration of Venus.Venera 5 was launched from a Tyazheliy Sputnik towards Venus to obtain atmospheric data...

 and Venera 6
Venera 6
Venera 6 was a Soviet spacecraft, launched from a Tyazheliy Sputnik on January 10, 1969 towards Venus to obtain atmospheric data. It had an on-orbit dry mass of 1130 kg....

 five days apart in January 1969; they encountered Venus a day apart on May 16 and May 17 that year. The probes were strengthened to improve their crush depth to 25 bar and were equipped with smaller parachutes to achieve a faster descent. Since then-current atmospheric models of Venus suggested a surface pressure of between 75 and 100 bar, neither was expected to survive to the surface. After returning atmospheric data for a little over fifty minutes, they both were crushed at altitudes of approximately 20 km before going on to strike the surface on the night side of Venus.

Surface and atmospheric science



Venera 7
Venera 7
The Venera 7 was a Soviet spacecraft, part of the Venera series of probes to Venus. When it landed on the Venusian surface, it became the first man-made spacecraft to successfully land on another planet and to transmit data from there back to Earth.*Launch date/time: 1970 August 17 at 05:38...

 represented an effort to return data from the planet's surface, and was constructed with a reinforced descent module capable of withstanding a pressure of 180 bar. The module was pre-cooled before entry and equipped with a specially reefed
Reefing
Reefing is a sailing manoeuvre intended to reduce the area of a sail on a sailboat or sailing ship, which can improve the ship's stability and reduce the risk of capsizing, broaching, or damaging sails or boat hardware in a strong wind...

 parachute for a rapid 35-minute descent. Entering the atmosphere on December 15, 1970, the parachute is believed to have partially torn during the descent, and the probe struck the surface with a hard, yet not fatal, impact. Probably tilted onto its side, it returned a weak signal supplying temperature data for 23 minutes, the first telemetry
Telemetry
Telemetry is a technology that allows measurements to be made at a distance, usually via radio wave transmission and reception of the information. The word is derived from Greek roots: tele = remote, and metron = measure...

 received from the surface of another planet.

The Venera program continued with Venera 8
Venera 8
Venera 8 was a probe in the Soviet Venera program for the exploration of Venus.Venera 8 was a Venus atmospheric probe and lander. Its instrumentation included temperature, pressure, and light sensors as well as an altimeter, gamma ray spectrometer, gas analyzer, and radio transmitters...

 sending data from the surface for 50 minutes, after entering the atmosphere on July 22, 1972. Venera 9
Venera 9
Venera 9 was a USSR unmanned space mission to Venus. It consisted of an orbiter and a lander. It was launched on June 8, 1975 02:38:00 UTC and weighed 4,936 kg...

, which entered the atmosphere of Venus on October 22, 1975, and Venera 10
Venera 10
Venera 10 was a USSR unmanned space mission to Venus. It consisted of an orbiter and a lander. It launched on June 14, 1975 03:00:31 UTC.-Orbiter:The orbiter entered Venus orbit on October 23, 1975...

, which entered the atmosphere three days later on October 25, sent the first images of the Venusian landscape. The two landing sites presented very different terrain in the immediate vicinities of the landers: Venera 9 had landed on a 20 degree slope scattered with boulders around 30–40 cm across; Venera 10 showed basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...

-like rock slabs interspersed with weathered
Weathering
Weathering is the breaking down of rocks, soils and minerals as well as artificial materials through contact with the Earth's atmosphere, biota and waters...

 material.

In the meantime, the United States had sent the Mariner 10
Mariner 10
Mariner 10 was an American robotic space probe launched by NASA on November 3, 1973, to fly by the planets Mercury and Venus. It was launched approximately two years after Mariner 9 and was the last spacecraft in the Mariner program...

 probe on a gravitational slingshot
Gravitational slingshot
In orbital mechanics and aerospace engineering, a gravitational slingshot, gravity assist maneuver, or swing-by is the use of the relative movement and gravity of a planet or other celestial body to alter the path and speed of a spacecraft, typically in order to save propellant, time, and expense...

 trajectory past Venus on its way to Mercury
Mercury (planet)
Mercury is the innermost and smallest planet in the Solar System, orbiting the Sun once every 87.969 Earth days. The orbit of Mercury has the highest eccentricity of all the Solar System planets, and it has the smallest axial tilt. It completes three rotations about its axis for every two orbits...

. On February 5, 1974, Mariner 10 passed within 5790 km of Venus, returning over 4000 photographs as it did so. The images, the best then achieved, showed the planet to be almost featureless in visible light, but ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...

 light revealed details in the clouds that had never been seen in Earth-bound observations.

The American Pioneer Venus project
Pioneer Venus project
The Pioneer mission to Venus consisted of two components, launched separately. Pioneer Venus 1 or Pioneer Venus Orbiter was launched in 1978 and studied the planet for more than a decade after orbital insertion in 1978. Pioneer Venus 2 or Pioneer Venus Multiprobe sent four small probes into the...

 consisted of two separate missions. The Pioneer Venus Orbiter was inserted into an elliptical orbit around Venus on December 4, 1978, and remained there for over thirteen years studying the atmosphere and mapping the surface with radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

. The Pioneer Venus Multiprobe released a total of four probes which entered the atmosphere on December 9, 1978, returning data on its composition, winds and heat fluxes.

Four more Venera lander missions took place over the next four years, with Venera 11
Venera 11
The Venera 11 was a USSR unmanned space mission part of the Venera program to explore the planet Venus. Venera 11 was launched on 9 September 1978 at 3:25:39 UTC....

 and Venera 12
Venera 12
The Venera 12 was an USSR unmanned space mission to explore the planet Venus. Venera 12 was launched on 14 September 1978 at 02:25:13 UTC. Separating from its flight platform on December 19, 1978, the lander entered the Venus atmosphere two days later at 11.2 km/s. During the descent, it...

 detecting Venusian electrical storm
Electrical storm
Electrical storm may refer to:* A thunderstorm* A medical condition of chaotic electrical activity of the heart, usually manifested by ventricular tachycardia* "Electrical Storm" , song by U2...

s; and Venera 13
Venera 13
Venera 13 was a probe in the Soviet Venera program for the exploration of Venus.Venera 13 and 14 were identical spacecraft built to take advantage of the 1981 Venus launch opportunity and launched 5 days apart, Venera 13 on 1981-10-30 at 06:04:00 UTC and Venera 14 on 1981-11-04 at 05:31:00 UTC,...

 and Venera 14
Venera 14
Venera 14 was a probe in the Soviet Venera program for the exploration of Venus.Venera 14 was identical to the Venera 13 spacecraft and built to take advantage of the 1981 Venus launch opportunity and launched 5 days apart...

, landing four days apart on March 1 and March 5, 1982, returning the first color photographs of the surface. All four missions deployed parachutes for braking in the upper atmosphere, but released them at altitudes of 50 km, the dense lower atmosphere providing enough friction to allow for an unaided soft landing. Both Venera 13 and 14 analyzed soil samples with an on-board X-ray fluorescence
X-ray fluorescence
X-ray fluorescence is the emission of characteristic "secondary" X-rays from a material that has been excited by bombarding with high-energy X-rays or gamma rays...

 spectrometer
Spectrometer
A spectrometer is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. The variable measured is most often the light's intensity but could also, for instance, be the polarization...

, and attempted to measure the compressibility of the soil with an impact probe. Venera 14, though, had the misfortune to strike its own ejected camera lens cap and its probe failed to contact the soil. The Venera program came to a close in October 1983 when Venera 15
Venera 15
Venera 15 was a spacecraft sent to Venus by the Soviet Union. This unmanned orbiter was to map the surface of Venus using high resolution imaging systems...

 and Venera 16
Venera 16
Venera 16 was a spacecraft sent to Venus by the Soviet Union. This unmanned orbiter was to map the surface of Venus using high resolution imaging systems...

 were placed in orbit to conduct mapping of the Venusian terrain with synthetic aperture radar
Synthetic aperture radar
Synthetic-aperture radar is a form of radar whose defining characteristic is its use of relative motion between an antenna and its target region to provide distinctive long-term coherent-signal variations that are exploited to obtain finer spatial resolution than is possible with conventional...

.

In 1985 the Soviet Union took advantage of the opportunity to combine missions to Venus and Comet Halley
Comet Halley
Halley's Comet or Comet Halley is the best-known of the short-period comets, and is visible from Earth every 75 to 76 years. Halley is the only short-period comet that is clearly visible to the naked eye from Earth, and thus the only naked-eye comet that might appear twice in a human lifetime...

, which passed through the inner Solar System that year. En route to Halley, on June 11 and June 15, 1985 the two spacecraft
Spacecraft
A spacecraft or spaceship is a craft or machine designed for spaceflight. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and transportation of humans and cargo....

 of the Vega program
Vega program
The Vega program was a series of Venus missions which also took advantage of the appearance of Comet Halley in 1986. Vega 1 and Vega 2 were unmanned spacecraft launched in a cooperative effort among the Soviet Union and Austria, Bulgaria, Hungary, the German Democratic Republic, Poland,...

 each dropped a Venera-style probe (of which Vega 1's partially failed) and released a balloon-supported aerobot
Aerobot
An aerobot is an aerial robot, usually used in the context of an unmanned space probe or unmanned aerial vehicle.While work has been done since the 1960s on robot "rovers" to explore the Moon and other worlds in the Solar system, such machines have limitations...

 into the upper atmosphere. The balloons achieved an equilibrium altitude of around 53 km, where pressure and temperature are comparable to those at Earth's surface. They remained operational for around 46 hours, and discovered that the Venusian atmosphere was more turbulent than previously believed, and subject to high winds and powerful convection cell
Convection cell
A convection cell is a phenomenon of fluid dynamics that occurs in situations where there are density differences within a body of liquid or gas. The convection usually requires a gravitational field but in microgravity experiments, thermal convection has been observed without gravitational effects...

s.

Radar mapping



The United States' Magellan probe
Magellan probe
The Magellan spacecraft, also referred to as the Venus Radar Mapper, was a 1,035-kilogram robotic space probe launched by NASA on May 4, 1989, to map the surface of Venus using Synthetic Aperture Radar and measure the planetary gravity...

 was launched on May 4, 1989 with a mission to map the surface of Venus with radar. The high-resolution images it obtained during its 4½ years of operation far surpassed all prior maps and were comparable to visible-light photographs of other planets. Magellan imaged over 98% of the Venusian surface by radar and mapped 95% of its gravity field. In 1994, at the end of its mission, Magellan was deliberately sent to its destruction into the atmosphere of Venus to quantify its density. Venus was observed by the Galileo
Galileo spacecraft
Galileo was an unmanned spacecraft sent by NASA to study the planet Jupiter and its moons. Named after the astronomer and Renaissance pioneer Galileo Galilei, it was launched on October 18, 1989 by the Space Shuttle Atlantis on the STS-34 mission...

 and Cassini
Cassini-Huygens
Cassini–Huygens is a joint NASA/ESA/ASI spacecraft mission studying the planet Saturn and its many natural satellites since 2004. Launched in 1997 after nearly two decades of gestation, it includes a Saturn orbiter and an atmospheric probe/lander for the moon Titan, although it has also returned...

 spacecraft during flybys on their respective missions to the outer planets, but Magellan would otherwise be the last dedicated mission to Venus for over a decade.

Current and future missions


NASA's MESSENGER
MESSENGER
The MErcury Surface, Space ENvironment, GEochemistry and Ranging space probe is a robotic NASA spacecraft in orbit around the planet Mercury. The spacecraft was launched aboard a Delta II rocket in August 2004 to study the chemical composition, geology, and magnetic field of Mercury...

 mission to Mercury performed two flybys of Venus in October 2006 and June 2007, to slow its trajectory for an eventual orbital insertion of Mercury in March 2011. MESSENGER collected scientific data on both those flybys.

The Venus Express
Venus Express
Venus Express is the first Venus exploration mission of the European Space Agency. Launched in November 2005, it arrived at Venus in April 2006 and has been continuously sending back science data from its polar orbit around Venus. Equipped with seven science instruments, the main objective of the...

 probe was designed and built by the European Space Agency
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...

. Launched on November 9, 2005 by a Russian Soyuz-Fregat rocket procured through Starsem
Starsem
Starsem is a European-Russian company that was created in 1996 to commercialise the Soyuz launcher. Starsem is headquartered in Évry, France and has the following shareholders:* Russian Federal Space Agency...

, it successfully assumed a polar orbit
Polar orbit
A polar orbit is an orbit in which a satellite passes above or nearly above both poles of the body being orbited on each revolution. It therefore has an inclination of 90 degrees to the equator...

 around Venus on April 11, 2006. The probe is undertaking a detailed study of the Venusian atmosphere and clouds, including mapping of the planet's plasma
Plasma (physics)
In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...

 environment and surface characteristics, particularly temperatures. One of the first results emerging from Venus Express is the discovery that a huge double atmospheric vortex
Polar vortex
A polar vortex is a persistent, large-scale cyclone located near one or both of a planet's geographical poles. On Earth, the polar vortices are located in the middle and upper troposphere and the stratosphere...

 exists at the south pole of the planet.


The Japan Aerospace Exploration Agency
Japan Aerospace Exploration Agency
The , or JAXA, is Japan's national aerospace agency. Through the merger of three previously independent organizations, JAXA was formed on October 1, 2003, as an Independent Administrative Institution administered by the Ministry of Education, Culture, Sports, Science and Technology and the...

 (JAXA) devised a Venus orbiter, Akatsuki (formerly "Planet-C"), which was launched on May 20, 2010 but the craft failed to enter orbit in December 2010. Hopes remain that the probe can successfully hibernate and make another insertion attempt in six years. Planned investigations included surface imaging with an infrared camera and experiments designed to confirm the presence of lightning
Lightning
Lightning is an atmospheric electrostatic discharge accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...

 as well as the determination of the existence of current surface volcanism
Volcanism
Volcanism is the phenomenon connected with volcanoes and volcanic activity. It includes all phenomena resulting from and causing magma within the crust or mantle of a planet to rise through the crust and form volcanic rocks on the surface....

.

The European Space Agency
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...

 (ESA) hopes to launch a mission to Mercury in 2014, called BepiColombo
BepiColombo
BepiColombo is a joint mission of the European Space Agency and the Japan Aerospace Exploration Agency to the planet Mercury, due to launch in 2014. The mission is still in the planning stages so changes to the current description are likely over the next few years...

, which will perform two flybys of Venus before it reaches Mercury orbit in 2020.

Under its New Frontiers Program
New Frontiers program
The New Frontiers program is a series of space exploration missions being conducted by NASA with the purpose of researching several of the Sun's planets including Jupiter, Venus, and the dwarf planet Pluto...

, NASA has proposed a lander mission called the Venus In-Situ Explorer
Venus In-Situ Explorer
The Venus In-Situ Explorer is a mission that was proposed by the NASA planetary science Decadal Survey as a space probe designed to answer fundamental scientific questions by landing and performing experiments on Venus...

 to land on Venus to study surface conditions and investigate the elemental and mineralogical features of the regolith
Regolith
Regolith is a layer of loose, heterogeneous material covering solid rock. It includes dust, soil, broken rock, and other related materials and is present on Earth, the Moon, some asteroids, and other terrestrial planets and moons.-Etymology:...

. The probe would be equipped with a core sampler to drill into the surface and study pristine rock samples not weathered by the very harsh surface conditions. The Venera-D
Venera-D
The Venera-D probe is a proposed Russian space probe to Venus, to be launched around 2016. Venera-D's prime purpose is to make remote-sensing observations around the planet Venus in a manner similar to that of the U.S. Magellan spacecraft in the 1990s, but with the use of more powerful radar....

 (Russian: Венера-Д) probe is a proposed Russian space probe to Venus, to be launched around 2016 with its goal to make remote-sensing observations around the planet Venus and deploying a lander, based on the Venera design, capable of surviving for a long duration on the planet's surface. Other proposed Venus exploration concepts include rovers, balloons, and airplanes.

NASA has recommended the Surface and Atmosphere Geochemical Explorer (SAGE) candidate mission to land on Venus, with a possible launch in 2016.

Manned flyby



A manned Venus flyby mission, using Apollo program hardware, was proposed in the late 1960s. The mission was planned to launch in late October or early November 1973, and would have used a Saturn V
Saturn V
The Saturn V was an American human-rated expendable rocket used by NASA's Apollo and Skylab programs from 1967 until 1973. A multistage liquid-fueled launch vehicle, NASA launched 13 Saturn Vs from the Kennedy Space Center, Florida with no loss of crew or payload...

 to send three men to fly past Venus in a flight lasting approximately one year. The spacecraft would have passed approximately 5,000 kilometres from the surface of Venus about four months later.

Timeline


This is a list of attempted and successful spacecraft that have left Earth to explore Venus more closely. Venus has also been imaged by the Hubble Space Telescope
Hubble Space Telescope
The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...

 in Earth orbit, and distant telescopic observations is another source of information about Venus.

Timeline by NASA Goddard Space Flight Center (up to 2011)
Responsible Mission Launch Elements and Result Notes
USSR   Sputnik 7
Sputnik 7
Tyazhely Sputnik, , also known as Venera 1VA No.1, and in the West as Sputnik 7, was a Soviet spacecraft, which was intended to be the first spacecraft to explore Venus. Due to a problem with its upper stage it failed to leave low Earth orbit...

 
Impact (attempted)
USSR   Venera 1
Venera 1
On February 12, 1961, 00:34:36 UTC, was the first planetary probe launched to Venus by the Soviet Union. The Venus-1 Automatic Interplanetary Station, or Venera 1, was a 643.5 kg probe consisting of a cylindrical body 1.05 metres in diameter topped by a dome, totalling 2.035 metres...

 
Flyby (contact lost)
USA   Mariner 1
Mariner 1
Mariner 1 was the first spacecraft of the American Mariner program. Launched on July 22, 1962 as a Venus flyby mission, a range safety officer ordered its destructive abort at 09:26:16 UT, 294.5 seconds after launch....

 
Flyby (launch failure)
USSR   Sputnik 19
Sputnik 19
Venera 2MV-1 No.1, also known as Sputnik 19 in the West, was a Soviet spacecraft, which was launched in 1962 as part of the Venera programme, and was intended to become the first spacecraft to land on Venus. Due to a problem with its upper stage it failed to leave low Earth orbit, and reentered the...

 
Flyby (attempted)
USA   Mariner 2
Mariner 2
Mariner 2 , an American space probe to Venus, was the first space probe to conduct a successful planetary encounter . The first successful spacecraft in the NASA Mariner program, it was a simplified version of the Block I spacecraft of the Ranger program and an exact copy of Mariner 1...

 
Flyby
USSR   Sputnik 20
Sputnik 20
Venera 2MV-1 No.2, also known as Sputnik 20 in the West, was a Soviet spacecraft, which was launched in 1962 as part of the Venera programme, and was intended to become the first spacecraft to land on Venus. Due to a problem with its upper stage it failed to leave low Earth orbit, and reentered the...

 
Flyby (attempted)
USSR   Sputnik 21
Sputnik 21
Venera 2MV-2 No.1, also known as Sputnik 21 in the West, was a Soviet spacecraft, which was launched in 1962 as part of the Venera programme, and was intended to make a flyby of Venus. Due to a problem with the rocket which launched it, it failed to leave low Earth orbit, and reentered the...

 
Flyby (attempted)
USSR   Cosmos 21
Cosmos 21
Kosmos 21 was a Soviet spacecraft with an unknown mission. This mission has been tentatively identified by NASA as a technology test of the Venera series space probes. It may have been an attempted Venus flyby, presumably similar to the later Kosmos 27 mission, or it may have been intended from...

 
Attempted Venera test flight?
USSR   Venera 1964A  Flyby (launch failure)
USSR   Venera 1964B  Flyby (launch failure)
USSR   Cosmos 27
Cosmos 27
Kosmos 27 was a space mission intended as a Venus flyby. The SL-6/A-2-e launcher successfully achieved Earth orbit, but the spacecraft failed to escape orbit for its flight to Venus....

 
Flyby (attempted)
USSR   Zond 1
Zond 1
Zond 1 was a member of the Soviet Zond program. It was the second Soviet research spacecraft to successfully reach Venus, although communications had failed by that time...

 
Flyby (contact lost)
USSR   Venera 2
Venera 2
Venera 2 was a probe in the Soviet Venera program for the exploration of Venus.*Launch Date/Time: 1965 November 12 at 05:02:00 UTC*On-orbit Dry Mass: 963 kg...

 
Flyby (contact lost)
USSR   Venera 3
Venera 3
Venera 3 was a Venera program space probe that was built and launched by the Soviet Union to explore the surface of Venus. It was launched on November 16, 1965 at 04:19 UTC from Baikonur, Kazakhstan....

 
Lander (contact lost)
USSR   Cosmos 96  Lander (attempted?)
USSR   Venera 1965A  Flyby (launch failure)
USSR   Venera 4
Venera 4
Venera 4 ) was a probe in the Soviet Venera program for the exploration of Venus. Venera-4 was the first successful probe to perform in-place analysis of the environment of another planet. It was also the first probe to land on another planet...

 
Probe
USA   Mariner 5
Mariner 5
Mariner 5 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 spectrum, and sample the solar particles and magnetic field fluctuations above the planet...

 
Flyby
USSR   Cosmos 167  Probe (attempted)
USSR   Venera 5
Venera 5
Venera 5 was a probe in the Soviet space program Venera for the exploration of Venus.Venera 5 was launched from a Tyazheliy Sputnik towards Venus to obtain atmospheric data...

 
Probe
USSR   Venera 6
Venera 6
Venera 6 was a Soviet spacecraft, launched from a Tyazheliy Sputnik on January 10, 1969 towards Venus to obtain atmospheric data. It had an on-orbit dry mass of 1130 kg....

 
Probe
USSR   Venera 7
Venera 7
The Venera 7 was a Soviet spacecraft, part of the Venera series of probes to Venus. When it landed on the Venusian surface, it became the first man-made spacecraft to successfully land on another planet and to transmit data from there back to Earth.*Launch date/time: 1970 August 17 at 05:38...

 
Lander
USSR   Cosmos 359  Probe (attempted)
USSR   Venera 8
Venera 8
Venera 8 was a probe in the Soviet Venera program for the exploration of Venus.Venera 8 was a Venus atmospheric probe and lander. Its instrumentation included temperature, pressure, and light sensors as well as an altimeter, gamma ray spectrometer, gas analyzer, and radio transmitters...

 
Probe
USSR   Cosmos 482
Cosmos 482
Kosmos 482 , launched March 31, 1972 at 04:02:33 UTC, was an attempted Venus probe which failed to escape low Earth orbit.Beginning in 1962, the name Kosmos was given to Soviet spacecraft which remained in Earth orbit, regardless of whether that was their intended final destination...

 
Probe (attempted)
USA   Mariner 10
Mariner 10
Mariner 10 was an American robotic space probe launched by NASA on November 3, 1973, to fly by the planets Mercury and Venus. It was launched approximately two years after Mariner 9 and was the last spacecraft in the Mariner program...

 
Flyby Mercury flyby
USSR   Venera 9
Venera 9
Venera 9 was a USSR unmanned space mission to Venus. It consisted of an orbiter and a lander. It was launched on June 8, 1975 02:38:00 UTC and weighed 4,936 kg...

 
Orbiter and lander
USSR   Venera 10
Venera 10
Venera 10 was a USSR unmanned space mission to Venus. It consisted of an orbiter and a lander. It launched on June 14, 1975 03:00:31 UTC.-Orbiter:The orbiter entered Venus orbit on October 23, 1975...

 
Orbiter and lander
USA   Pioneer Venus 1  Orbiter
USA   Pioneer Venus 2  Probes
USSR   Venera 11
Venera 11
The Venera 11 was a USSR unmanned space mission part of the Venera program to explore the planet Venus. Venera 11 was launched on 9 September 1978 at 3:25:39 UTC....

 
Flyby bus and lander
USSR   Venera 12
Venera 12
The Venera 12 was an USSR unmanned space mission to explore the planet Venus. Venera 12 was launched on 14 September 1978 at 02:25:13 UTC. Separating from its flight platform on December 19, 1978, the lander entered the Venus atmosphere two days later at 11.2 km/s. During the descent, it...

 
Flyby bus and lander
USSR   Venera 13
Venera 13
Venera 13 was a probe in the Soviet Venera program for the exploration of Venus.Venera 13 and 14 were identical spacecraft built to take advantage of the 1981 Venus launch opportunity and launched 5 days apart, Venera 13 on 1981-10-30 at 06:04:00 UTC and Venera 14 on 1981-11-04 at 05:31:00 UTC,...

 
Flyby bus and lander
USSR   Venera 14
Venera 14
Venera 14 was a probe in the Soviet Venera program for the exploration of Venus.Venera 14 was identical to the Venera 13 spacecraft and built to take advantage of the 1981 Venus launch opportunity and launched 5 days apart...

 
Flyby bus and lander
USSR   Venera 15
Venera 15
Venera 15 was a spacecraft sent to Venus by the Soviet Union. This unmanned orbiter was to map the surface of Venus using high resolution imaging systems...

 
Orbiter
USSR   Venera 16
Venera 16
Venera 16 was a spacecraft sent to Venus by the Soviet Union. This unmanned orbiter was to map the surface of Venus using high resolution imaging systems...

 
Orbiter
USSR   Vega 1
Vega 1
Vega 1 is a Soviet space probe part of the Vega program. The spacecraft was a development of the earlier Venera craft...

 
Lander and balloon Comet Halley flyby
USSR   Vega 2
Vega 2
Vega 2 is a Soviet space probe part of the Vega program. The spacecraft was a development of the earlier Venera craft. They were designed by Babakin Space Center and constructed as 5VK by Lavochkin at Khimki...

 
Lander and balloon Comet Halley flyby
USA   Magellan  Orbiter
USA   Galileo  Flyby Jupiter orbiter/probe
USA   Cassini  Flyby Saturn orbiter
USA   MESSENGER
MESSENGER
The MErcury Surface, Space ENvironment, GEochemistry and Ranging space probe is a robotic NASA spacecraft in orbit around the planet Mercury. The spacecraft was launched aboard a Delta II rocket in August 2004 to study the chemical composition, geology, and magnetic field of Mercury...

 
Flyby (x2) Mercury orbiter
ESA Venus Express
Venus Express
Venus Express is the first Venus exploration mission of the European Space Agency. Launched in November 2005, it arrived at Venus in April 2006 and has been continuously sending back science data from its polar orbit around Venus. Equipped with seven science instruments, the main objective of the...

 
Orbiter
JPN   Akatsuki  Orbiter (attempted) Possible reattempt in 2016
ESA
JPN  
BepiColombo
BepiColombo
BepiColombo is a joint mission of the European Space Agency and the Japan Aerospace Exploration Agency to the planet Mercury, due to launch in 2014. The mission is still in the planning stages so changes to the current description are likely over the next few years...

 
Flyby (x2, Planned) Planned Mercury orbiter

In culture


The adjective Venusian
Venusian
Venusian, Venerean or Venerial may refer to:*Of or relating to the planet Venus*Venusians, hypothetical or fictional beings that inhabit the planet Venus...

is commonly used for items related to Venus, though the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 adjective is the rarely used Venerean; the archaic Cytherean
Cytherean
Cytherean is an adjective meaning pertaining to Cythera , a small island now part of Greece, southeast of the Peloponnesus. It is also an adjective meaning pertaining to the planet Venus.When planetary scientists began to have a need to discuss Venus in detail, an adjective was needed...

is still occasionally encountered. Venus is the only planet in the Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...

 that is named after a female
Female
Female is the sex of an organism, or a part of an organism, which produces non-mobile ova .- Defining characteristics :The ova are defined as the larger gametes in a heterogamous reproduction system, while the smaller, usually motile gamete, the spermatozoon, is produced by the male...

 figure. (Three dwarf planet
Dwarf planet
A dwarf planet, as defined by the International Astronomical Union , is a celestial body orbiting the Sun that is massive enough to be spherical as a result of its own gravity but has not cleared its neighboring region of planetesimals and is not a satellite...

s – Ceres, Eris
Eris (dwarf planet)
Eris, formal designation 136199 Eris, is the most massive known dwarf planet in the Solar System and the ninth most massive body known to orbit the Sun directly...

 and Haumea – along with many of the first discovered asteroids and a number of moons (such as the Galilean moons
Galilean moons
The Galilean moons are the four moons of Jupiter discovered by Galileo Galilei in January 1610. They are the largest of the many moons of Jupiter and derive their names from the lovers of Zeus: Io, Europa, Ganymede and Callisto. Ganymede, Europa and Io participate in a 1:2:4 orbital resonance...

) also have feminine
Feminine
Feminine, or femininity, normally refers to qualities positively associated with women.Feminine may also refer to:*Feminine , a grammatical gender*Feminine cadence, a final chord falling in a metrically weak position...

 names. Earth and its moon also have feminine names in many languages – Gaia/Terra, Selene/Luna – but the female mythological figures who personified them were named after them, not the other way around.)

Historic understanding




As one of the brightest objects in the sky, Venus has been known since prehistoric times and as such has gained an entrenched position in human culture. It is described in Babylon
Babylon
Babylon was an Akkadian city-state of ancient Mesopotamia, the remains of which are found in present-day Al Hillah, Babil Province, Iraq, about 85 kilometers south of Baghdad...

ian cuneiformic
Cuneiform script
Cuneiform script )) is one of the earliest known forms of written expression. Emerging in Sumer around the 30th century BC, with predecessors reaching into the late 4th millennium , cuneiform writing began as a system of pictographs...

 texts such as the Venus tablet of Ammisaduqa
Venus tablet of Ammisaduqa
The Venus tablet of Ammisaduqa refers to the record of astronomical observations of Venus, as preserved in numerous cuneiform tablets dating from the first millennium BCE. It is believed that this astronomical record was first compiled during the reign of King Ammisaduqa , the fourth ruler after...

, which relates observations that possibly date from 1600 BC. The Babylonians named the planet Ishtar
Ishtar
Ishtar is the Assyrian and Babylonian goddess of fertility, love, war, and sex. She is the counterpart to the Sumerian Inanna and to the cognate north-west Semitic goddess Astarte.-Characteristics:...

(Sumerian Inanna
Inanna
Inanna, also spelled Inana is the Sumerian goddess of sexual love, fertility, and warfare....

), the personification of womanhood, and goddess of love.

The Ancient Egypt
Ancient Egypt
Ancient Egypt was an ancient civilization of Northeastern Africa, concentrated along the lower reaches of the Nile River in what is now the modern country of Egypt. Egyptian civilization coalesced around 3150 BC with the political unification of Upper and Lower Egypt under the first pharaoh...

ians believed Venus to be two separate bodies and knew the morning star as Tioumoutiri and the evening star as Ouaiti. Likewise, believing Venus to be two bodies, the Ancient Greeks
Ancient Greece
Ancient Greece is a civilization belonging to a period of Greek history that lasted from the Archaic period of the 8th to 6th centuries BC to the end of antiquity. Immediately following this period was the beginning of the Early Middle Ages and the Byzantine era. Included in Ancient Greece is the...

 called the morning star , (Latinized Phosphorus
Hesperus
In Greek mythology, Hesperus is the Evening Star, the planet Venus in the evening. He is the son of the dawn goddess Eos and is the brother of Eosphorus , the Morning Star. Hesperus' Roman equivalent is Vesper...

), the "Bringer of Light" or , (Latinized Eosphorus), the "Bringer of Dawn". The evening star they called (Latinized Hesperus
Hesperus
In Greek mythology, Hesperus is the Evening Star, the planet Venus in the evening. He is the son of the dawn goddess Eos and is the brother of Eosphorus , the Morning Star. Hesperus' Roman equivalent is Vesper...

) . By Hellenistic times, the ancient Greeks realized the two were the same planet, which they named after their goddess of love, Aphrodite
Aphrodite
Aphrodite is the Greek goddess of love, beauty, pleasure, and procreation.Her Roman equivalent is the goddess .Historically, her cult in Greece was imported from, or influenced by, the cult of Astarte in Phoenicia....

 (Phoenician Astarte
Astarte
Astarte is the Greek name of a goddess known throughout the Eastern Mediterranean from the Bronze Age to Classical times...

). Hesperos
Hesperus
In Greek mythology, Hesperus is the Evening Star, the planet Venus in the evening. He is the son of the dawn goddess Eos and is the brother of Eosphorus , the Morning Star. Hesperus' Roman equivalent is Vesper...

 would be translated into Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 as Vesper and Phosphoros as Lucifer
Lucifer
Traditionally, Lucifer is a name that in English generally refers to the devil or Satan before being cast from Heaven, although this is not the original meaning of the term. In Latin, from which the English word is derived, Lucifer means "light-bearer"...

 ("Light Bearer"), a poetic term later used to refer to the fallen angel cast out of heaven. The Romans
Ancient Rome
Ancient Rome was a thriving civilization that grew on the Italian Peninsula as early as the 8th century BC. Located along the Mediterranean Sea and centered on the city of Rome, it expanded to one of the largest empires in the ancient world....

, who derived much of their religious pantheon from the Greek tradition, named the planet Venus
Venus (mythology)
Venus is a Roman goddess principally associated with love, beauty, sex,sexual seduction and fertility, who played a key role in many Roman religious festivals and myths...

 after their goddess of love. Pliny the Elder
Pliny the Elder
Gaius Plinius Secundus , better known as Pliny the Elder, was a Roman author, naturalist, and natural philosopher, as well as naval and army commander of the early Roman Empire, and personal friend of the emperor Vespasian...

 (Natural History, ii,37) identified the planet Venus with Isis
Isis
Isis or in original more likely Aset is a goddess in Ancient Egyptian religious beliefs, whose worship spread throughout the Greco-Roman world. She was worshipped as the ideal mother and wife as well as the matron of nature and magic...

.

In Iranian mythology
Iranian mythology
Iranian mythologies include:*Persian mythology*Scythian mythology*Ossetic mythology...

, especially in Persian mythology
Persian mythology
Persian mythology are traditional tales and stories of ancient origin, some involving extraordinary or supernatural beings. Drawn from the legendary past of the Iranian cultural continent which especially consists of the state of Iran, Afghanistan, Tajikistan and Central Asia, they reflect the...

, the planet usually corresponds to the goddess Anahita
Anahita
Anahita is the Old Persian form of the name of an Iranian goddess and appears in complete and earlier form as ' ; the Avestan language name of an Indo-Iranian cosmological figure venerated as the divinity of 'the Waters' and hence associated with fertility, healing and wisdom...

. In some parts of Pahlavi
Pahlavi scripts
Pahlavi or Pahlevi denotes a particular and exclusively written form of various Middle Iranian languages. The essential characteristics of Pahlavi are*the use of a specific Aramaic-derived script, the Pahlavi script;...

 literature the deities Aredvi Sura and Anahita are regarded as separate entities, the first one as a personification of the mythical river and the latter as a goddess of fertility which is associated with the planet Venus. As the goddess Aredvi Sura Anahita—and simply called Anahita as well—both deities are unified in other descriptions, e. g. in the Greater Bundahishn
Bundahishn
Bundahishn, meaning "Primal Creation", is the name traditionally given to an encyclopædiaic collections of Zoroastrian cosmogony and cosmology written in Book Pahlavi. The original name of the work is not known....

, and are represented by the planet. In the Avesta
Avesta
The Avesta is the primary collection of sacred texts of Zoroastrianism, composed in the Avestan language.-Early transmission:The texts of the Avesta — which are all in the Avestan language — were composed over the course of several hundred years. The most important portion, the Gathas,...

n text Mehr Yasht
Yasht
The s are a collection of twenty-one hymns in Younger Avestan. Each of these hymns invokes a specific Zoroastrian divinity or concept. Yasht chapter and verse pointers are traditionally abbreviated as Yt....

 (Yasht 10) there is a possible early link to Mithra
Mithra
Mithra is the Zoroastrian divinity of covenant and oath. In addition to being the divinity of contracts, Mithra is also a judicial figure, an all-seeing protector of Truth, and the guardian of cattle, the harvest and of The Waters....

. The Persian
Persian language
Persian is an Iranian language within the Indo-Iranian branch of the Indo-European languages. It is primarily spoken in Iran, Afghanistan, Tajikistan and countries which historically came under Persian influence...

 name of the planet today is "Nahid" which derives from Anahita and later in history from the Pahlavi language Anahid.

The planet Venus was important to the Maya civilization
Maya civilization
The Maya is a Mesoamerican civilization, noted for the only known fully developed written language of the pre-Columbian Americas, as well as for its art, architecture, and mathematical and astronomical systems. Initially established during the Pre-Classic period The Maya is a Mesoamerican...

, who developed a religious calendar
Maya calendar
The Maya calendar is a system of calendars and almanacs used in the Maya civilization of pre-Columbian Mesoamerica, and in many modern Maya communities in highland Guatemala. and in Chiapas....

 based in part upon its motions, and held the motions of Venus to determine the propitious time for events such as war. They named it Noh Ek', the Great Star, and Xux Ek', the Wasp Star. The Maya were aware of the planet's synodic period, and could compute it to within a hundredth part of a day.

The Maasai people named the planet Kileken
Kileken
Kileken is the subject of a myth of the Maasai people concerning the planet Venus. In the myth, the planet Venus is called Kileken, and visits the Earth in the form of a small boy. The boy befriends an old farmer and tends his cattle, the man agreeing to let the boy keep the only thing he has: the...

, and have an oral tradition
Oral tradition
Oral tradition and oral lore is cultural material and traditions transmitted orally from one generation to another. The messages or testimony are verbally transmitted in speech or song and may take the form, for example, of folktales, sayings, ballads, songs, or chants...

 about it called The Orphan Boy.

Venus is important in many Australian aboriginal cultures
Australian Aboriginal astronomy
Australian Aboriginal astronomy is a name given to indigenous Australian culture relating to astronomical subjects — such as the Sun and Moon, the stars, planets, and the Milky Way, and their motions on the sky...

, such as that of the Yolngu
Yolngu
The Yolngu or Yolŋu are an Indigenous Australian people inhabiting north-eastern Arnhem Land in the Northern Territory of Australia. Yolngu means “person” in the Yolŋu languages.-Yolŋu law:...

 people in Northern Australia. The Yolngu gather after sunset to await the rising of Venus, which they call Barnumbirr
Barnumbirr
Barnumbirr is a creator-spirit in the Yolngu culture of Arnhem Land in Australia, who is identified as the planet Venus. She guided the first humans, the Djanggawul sisters, to Australia. The rising of Barnumbirr in the sky before sunrise marks an important ceremony of the Yolngu...

. As she approaches, in the early hours before dawn, she draws behind her a rope of light attached to the Earth, and along this rope, with the aid of a richly decorated "Morning Star Pole", the people are able to communicate with their dead loved ones, showing that they still love and remember them. Barnumbirr is also an important creator-spirit in the Dreaming
Dreaming (spirituality)
The Dreaming is a common term within the animist creation narrative of indigenous Australians for a personal, or group, creation and for what may be understood as the "timeless time" of formative creation and perpetual creating....

, and "sang" much of the country into life.

Venus plays a prominent role in Pawnee mythology
Pawnee mythology
Pawnee mythology is the body of myths and legends belonging to the Pawnee concerning their gods and heroes. The Pawnee are a federally recognized tribe of Native Americans, originally located on the Great Plains along tributaries of the Missouri River. They spoke a Caddoan language.-Beliefs and...

. The Pawnee, a North American native tribe, until as late as 1838, practiced a morning star ritual in which a girl was sacrificed to the morning star.


In western astrology
Astrology
Astrology consists of a number of belief systems which hold that there is a relationship between astronomical phenomena and events in the human world...

, derived from its historical connotation with goddesses of femininity and love, Venus is held to influence desire and sexual fertility. In Indian Vedic astrology, Venus is known as Shukra
Shukra
Shukra , the Sanskrit for "clear, pure" or "brightness, clearness", is the name of the son of Bhrigu, and preceptor of the Daityas, and the guru of the Asuras, identified with the planet Venus, one of the Navagrahas...

, meaning "clear, pure" or "brightness, clearness" in Sanskrit
Sanskrit
Sanskrit , is a historical Indo-Aryan language and the primary liturgical language of Hinduism, Jainism and Buddhism.Buddhism: besides Pali, see Buddhist Hybrid Sanskrit Today, it is listed as one of the 22 scheduled languages of India and is an official language of the state of Uttarakhand...

. One of the nine Navagraha
Navagraha
Graha is a 'cosmic influencer' on the living beings of mother Bhumidevi . In Hindu astrology, the Navagraha are some of these major influencers.All the navagraha have relative movement with respect to the background of fixed stars in the zodiac...

, it is held to affect wealth, pleasure and reproduction; it was the son of Bhrgu, preceptor of the Daityas, and guru of the Asuras. Modern Chinese, Korean, Japanese and Vietnamese cultures refer to the planet literally as the “metal star” (金星), based on the Five elements
Five elements (Chinese philosophy)
The Wu Xing, also known as the Five Phases, the Five Agents, the Five Movements, and the Five Steps/Stages, are chiefly an ancient mnemonic device, in many traditional Chinese fields....

.

In the metaphysical system of Theosophy
Theosophy
Theosophy, in its modern presentation, is a spiritual philosophy developed since the late 19th century. Its major themes were originally described mainly by Helena Blavatsky , co-founder of the Theosophical Society...

, it is believed that on the etheric plane
Etheric plane
The etheric plane is a term introduced into Theosophy by Charles Webster Leadbeater and Annie Besant to represent one of the planes of existence in neo-Theosophical and Rosicrucian cosmology. It represents the fourth[higher] subplane of the physical plane , the lower three being the states of...

 of Venus there is a civilization that existed hundreds of millions of years before Earth’s and it is also believed that the governing deity
Deity
A deity is a recognized preternatural or supernatural immortal being, who may be thought of as holy, divine, or sacred, held in high regard, and respected by believers....

 of Earth, Sanat Kumara
Sanat Kumara
According to the post-1900 publications of Theosophy, i.e. the writings of C. W. Leadbeater, Alice A. Bailey, and Benjamin Creme, as well as the Ascended Master Teachings of Guy Ballard, Elizabeth Clare Prophet, Geraldine Innocente, Joshua David Stone, and other Ascended Master Teachings teachers,...

, is from Venus.

The astronomical symbol
Astronomical symbols
Astronomical symbols are symbols used to represent various celestial objects, theoretical constructs and observational events in astronomy. The earliest forms of these symbols appear in Greek papyri of late antiquity. The Byzantine codices in which the Greek papyri were preserved continued and...

 for Venus is the same as that used in biology for the female
Female
Female is the sex of an organism, or a part of an organism, which produces non-mobile ova .- Defining characteristics :The ova are defined as the larger gametes in a heterogamous reproduction system, while the smaller, usually motile gamete, the spermatozoon, is produced by the male...

 sex
Sex
In biology, sex is a process of combining and mixing genetic traits, often resulting in the specialization of organisms into a male or female variety . Sexual reproduction involves combining specialized cells to form offspring that inherit traits from both parents...

: a circle with a small cross beneath. The Venus symbol also represents femininity
Femininity
Femininity is a set of attributes, behaviors, and roles generally associated with girls and women. Though socially constructed, femininity is made up of both socially defined and biologically created factors...

, and in Western alchemy
Alchemy
Alchemy is an influential philosophical tradition whose early practitioners’ claims to profound powers were known from antiquity. The defining objectives of alchemy are varied; these include the creation of the fabled philosopher's stone possessing powers including the capability of turning base...

 stood for the metal copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

. 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.

Perhaps the strangest appearance of Venus in literature is as the harbinger of destruction in Immanuel Velikovsky
Immanuel Velikovsky
Immanuel Velikovsky was a Russian-born American independent scholar of Jewish origins, best known as the author of a number of controversial books reinterpreting the events of ancient history, in particular the US bestseller Worlds in Collision, published in 1950...

's Worlds in Collision
Worlds in Collision
Worlds in Collision is a book written by Immanuel Velikovsky and first published on April 3, 1950. The book proposed that around the 15th century BCE, Venus was ejected from Jupiter as a comet or comet-like object, and passed near Earth...

(1950). In this intensely controversial book, Velikovsky argued that many seemingly unbelievable stories in the Old Testament are true recollections of times when Venus nearly collided with the Earth — when it was still a comet and had not yet become the docile planet that we know today. He contended that Venus caused most of the strange events of the Exodus. He cites legends in many other cultures (such as Greek, Mexican, Chinese and Indian) indicating that the effects of the near-collision were global. The scientific community rejected his wildly unorthodox book, but it became a bestseller.

In science fiction



The impenetrable Venusian cloud cover gave science fiction
Science fiction
Science fiction is a genre of fiction dealing with imaginary but more or less plausible content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities...

 writers free rein to speculate on conditions at its surface; all the more so when early observations showed that not only was it very 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
Planetary habitability
Planetary habitability is the measure of a planet's or a natural satellite's potential to sustain life. Life may develop directly on a planet or satellite or be transferred to it from another body, a theoretical process known as panspermia...

 by humans. The genre
Genre
Genre , Greek: genos, γένος) is the term for any category of literature or other forms of art or culture, e.g. music, and in general, any type of discourse, whether written or spoken, audial or visual, based on some set of stylistic criteria. Genres are formed by conventions that change over time...

 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 very different, and brought this particular genre to an end. As scientific knowledge of Venus advanced, so science fiction authors endeavored to keep pace, particularly by conjecturing human attempts to terraform Venus
Terraforming of Venus
The terraforming of Venus is the hypothetical process of engineering the global environment of the planet Venus in such a way as to make it suitable for human habitation. Terraforming Venus was first seriously proposed by the astronomer Carl Sagan in 1961. The minimum adjustments to the existing...

.

Colonization


Due to its extremely hostile conditions, a surface colony on Venus is out of the question with current technology. The atmospheric pressure and temperature approximately fifty kilometres above the surface are similar to those at the Earth's surface and Earth air (nitrogen and oxygen) would be a lifting gas in the Venusian atmosphere of mostly carbon dioxide. This has led to proposals for extensive "floating cities" in the Venusian atmosphere. Aerostat
Aerostat
An aerostat is a craft that remains aloft primarily through the use of buoyant lighter than air gases, which impart lift to a vehicle with nearly the same overall density as air. Aerostats include free balloons, airships, and moored balloons...

s (lighter-than-air balloons) could be used for initial exploration and ultimately for permanent settlements. Among the many engineering challenges are the dangerous amounts of sulfuric acid at these heights.

Namesakes


USS Venus (AK-135)
USS Venus (AK-135)
The USS Venus was a Crater-class cargo ship in the service of the United States Navy in World War II. Originally liberty ship SS William Williams , it was taken over by the Navy after being damaged in a torpedo attack and renamed after the planet Venus...

 was a United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

 Crater class cargo ship
Crater class cargo ship
Crater-class cargo ship is a category of freighter that was constructed for use by the United States Navy during World War II under Maritime Commission EC2-S-C1 type....

 named after the planet.

See also


  • Aspects of Venus
    Aspects of Venus
    The table contains special positions of Venus until 2021.Note: Greatest brilliancy is often confused with "maximum brightness". Although they are related, they are not quite the same thing. The "greatest brilliancy" is really a geometric maximum: it occurs when the apparent area of the sunlit...

  • Mariner 10 Space probe to Venus
    Mariner 10
    Mariner 10 was an American robotic space probe launched by NASA on November 3, 1973, to fly by the planets Mercury and Venus. It was launched approximately two years after Mariner 9 and was the last spacecraft in the Mariner program...



External links




Cartographic resources