Venus
Venus in real color
Epoch J2000
Aphelion108,942,109 km
0. In Physics, an orbit is the gravitationally curved path of one object around a point or another body for example the gravitational orbit of a planet around a star In Astronomy, an epoch is a moment in time used as a reference for the Orbital elements of a Celestial body. In Astronomy, an epoch is a moment in time used as a reference for the Orbital elements of a Celestial body. In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from 72823128 AU
Perihelion107,476,259 km
0. The astronomical unit ( AU or au or au or sometimes ua) is a unit of Length based on the distance from the Earth to the In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from 71843270 AU
Semi-major axis108,208,930 km
0. In Geometry, the semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae 723332 AU
Eccentricity0. In Astrodynamics, under standard assumptions, any Orbit must be of Conic section shape 0068
Orbital period224.70069 day
0. The orbital period is the time taken for a given object to make one complete Orbit about another object To help compare Orders of magnitude of different times this page lists times between 116 Days and 1157 days or 3 A day (symbol d is a unit of Time equivalent to 24 Hours and the duration of a single Rotation of planet Earth with respect to the 6151970 yr
Synodic period583. In Astronomy, a Julian year (symbol a) is a unit of measurement of Time defined The orbital period is the time taken for a given object to make one complete Orbit about another object 92 days[1]
Average orbital speed35. The orbital speed of a body generally a Planet, a Natural satellite, an artificial satellite, or a Multiple star, is the speed at which it 02 km/s
Inclination3. Inclination in general is the Angle between a Reference plane and another plane or axis of direction 39471°
3. 86° to Sun's equator
Longitude of ascending node76. The longitude of the ascending node (☊ or Ω is one of the Orbital elements used to specify the Orbit of an object in space 67069°
Argument of perihelion54. The argument of periapsis (or argument of perifocus) ( ω) is the Orbital element describing the Angle of an Orbiting body's periapsis 85229°
SatellitesNone
Physical characteristics
Mean radius6051. A natural satellite or moon is a Celestial body that Orbits a Planet or smaller body which is called the primary. 8 ± 1. 0 km[2]
0. 9499 Earths
Flattening< 0. Ellipticity redirects here For the mathematical topic of ellipticity see Elliptic operator. 0002[2]
Surface area4.60×108 km²
0. Equation A spheroid centered at the origin and rotated about the z axis is defined by the implicit equation \left(\frac{x}{a}\right^2+\left(\frac{y}{a}\right^2+\left(\frac{z}{b}\right^2 To help compare sizes of different Areas here is a list of areas between 100 million km² and 1000 million (American billion km² 902 Earths
Volume9. The volume of any solid plasma vacuum or theoretical object is how much three- Dimensional space it occupies often quantified numerically 38×1011 km³
0. 857 Earths
Mass4.8685×1024 kg
0. Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object To help compare different orders of magnitude, the following list describes various Mass levels between 10&minus36&thinsp kg and 1053&thinspkg 815 Earths
Mean density5. The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different 204 g/cm³
Equatorial surface gravity8. The surface gravity, g, of an astronomical or other object is the Gravitational acceleration experienced at its surface 87 m/s2
0. 904 g
Escape velocity10. g-force (also G-force, g-load) is a measurement of an object's Acceleration expressed in g s In Physics, escape velocity is the speed where the Kinetic energy of an object is equal to the magnitude of its Gravitational potential energy 46 km/s
Sidereal rotation
period
243. The rotation period of an astronomical object is the time it takes to complete one revolution around its Axis of rotation relative to the background stars Direct motion is the motion of a Planetary body in a direction similar to that of other bodies within its system and is sometimes called prograde motion. 0185 day
Equatorial rotation velocity6. 52 km/h
Axial tilt177. In Astronomy, axial tilt is the Inclination angle of a planet's rotational axis in relation to its orbital plane. 36°
North pole right ascension18 h 11 min 2 s
272. Right ascension (abbrev RA; symbol α) is the Astronomical term for one of the two Coordinates of a point on the Celestial sphere 76°[3]
North pole declination67. In Astronomy, declination (abbrev dec or δ) is one of the two coordinates of the Equatorial coordinate system, the other being either 16°
Albedo0. The albedo of an object is the extent to which it diffusely reflects light from the sun 65
Surface temp.
Kelvin
Celsius
minmeanmax
735 K[4][5]
461. Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic The Celsius Temperature scale was previously known as the centigrade scale. 85 °C
Apparent magnitudeup to -4. The apparent magnitude ( m) of a celestial body is a measure of its Brightness as seen by an observer on Earth, normalized to the value 6[1]
Angular diameter9. The angular diameter of an object as seen from a given position is the "visual diameter" of the object measured as an angle 7" — 66. 0"[1]
Atmosphere
Surface pressure9. Cytherean is an Adjective meaning pertaining to Cythera, a small island now part of Greece 3 MPa
Composition~96. 5% Carbon dioxide
~3. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single 5% Nitrogen
. Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 015% Sulfur dioxide
. 007% Argon
. This article pertains to the chemical element For other uses see Argon (disambiguation. 002% Water vapor
. General properties of water vapor Evaporation/sublimation Whenever a water molecule leaves a surface it is said to have evaporated 0017% Carbon monoxide
. Carbon monoxide, with the chemical formula CO is a colorless odorless tasteless yet highly toxic Gas. 0012% Helium
. Helium ( He) is a colorless odorless tasteless non-toxic Inert Monatomic Chemical 0007% Neon
trace Carbonyl sulfide
trace Hydrogen chloride
trace Hydrogen fluoride

Venus (pronounced [ˈviːnəs] ) is the second-closest planet to the Sun, orbiting it every 224. Neon (ˈniːɒn is the Chemical element that has the symbol Ne and Atomic number 10 Carbonyl sulfide is the Chemical compound with the formula OCS Structure HF forms orthorhombic crystals consisting of zig-zag chains of HF molecules A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is The Sun (Sol is the Star at the center of the Solar System. 7 Earth days. It is the brightest natural object in the night sky, except for the Moon, reaching an apparent magnitude of −4. The apparent magnitude ( m) of a celestial body is a measure of its Brightness as seen by an observer on Earth, normalized to the value 6. Because Venus is an inferior planet from Earth, it never appears to venture far from the Sun: its elongation reaches a maximum of 47. The terms " inferior planet " and " superior planet " were originally used in the Ptolemaic Cosmology to differentiate those planets EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 (For other uses of elongation see Elongation) Elongation is an Astronomical term that refers to the angle between the Sun and a planet 8°. Venus reaches its maximum brightness shortly before sunrise or shortly after sunset, for which reason it is often called the Morning Star or the Evening Star.

Classified as a terrestrial planet, it is sometimes called Earth's "sister planet", because the two are similar in size, gravity, and bulk composition. A terrestrial planet, telluric planet or rocky planet is a Planet that is primarily composed of Silicate rocks Within our Venus is covered with an opaque layer of highly reflective clouds of sulfuric acid, preventing its surface from being seen from space in visible light; this was a subject of great speculation until some of its secrets were revealed by planetary science in the twentieth century. A cloud is a visible mass of droplets or frozen crystals floating in the atmosphere above the surface of the Earth or another Planetary body Sulfuric (or sulphuric acid, H 2 S[[oxygen O]]4 is a strong Mineral acid. Planetary science, also known as planetology and closely related to planetary astronomy, is the Science of Planets or Planetary systems Venus has the densest atmosphere of all the terrestrial planets, consisting mostly of carbon dioxide, as it has no carbon cycle to lock carbon back into rocks and surface features, nor organic life to absorb it in biomass. An atmosphere (from Greek ατμός - atmos, " Vapor " + σφαίρα - sphaira, " Sphere " Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the Biosphere, Pedosphere, Geosphere, Hydrosphere, and It has become so hot that the earth-like oceans that the young Venus is believed to have possessed have totally evaporated, leaving a dusty dry desertscape with many slab-like rocks. The best hypothesis is that the evaporated water vapor has dissociated, and with the lack of a planetary magnetic field, the hydrogen has been swept into interplanetary space by the solar wind. The atmospheric pressure at the planet's surface is 92 times that of the Earth.

Venus's surface has been mapped in detail only in the last 22 years, by Project Magellan. The Magellan spacecraft was a space probe sent to the planet Venus, the first post- Voyager unmanned spacecraft to be launched by NASA It shows evidence of extensive volcanism, and the sulfur in the atmosphere is taken by some experts to show that there has been some recent volcanism, but it is an enigma as to why no evidence of lava flow accompanies any of the visible caldera. Plate tectonics and hotspots Divergent plate boundaries At the Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures A caldera is a cauldron-like volcanic feature formed by the collapse of land following a volcanic eruption It is also noteworthy that there are a surprisingly low number of impact craters. 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 larger body This demonstrates that the surface is relatively young, approximately half a billion years old. There is no evidence for plate tectonics, possibly because its crust is too strong to subduct without water to make it less viscous, and some suggest that instead Venus loses its internal heat in periodic massive resurfacing events. Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere In Geology, a subduction zone is an area on Earth where two tectonic plates meet and move towards one another with one sliding underneath the other Viscosity is a measure of the resistance of a Fluid which is being deformed by either Shear stress or Extensional stress.

The adjective Venusian is commonly used for items related to Venus, though the Latin adjective is the rarely used Venerean; the now-archaic Cytherean is still occasionally encountered. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. Cytherean is an Adjective meaning pertaining to Cythera, a small island now part of Greece Venus is the only planet in the Solar System named after a female figure,[a] although two dwarf planetsCeres and Eris—also have female names. The Solar System consists of the Sun and those celestial objects bound to it by Gravity. A dwarf planet, as defined by the International Astronomical Union (IAU is a Celestial body Orbiting the Sun that is massive enough to be rounded Ceres (ˈsɪəriːz Female (♀ is the Sex of an Organism, or a part of an organism which produces ova (egg cells

## Physical characteristics

Venus is one of the four solar terrestrial planets, meaning that, like the Earth, it is a rocky body. A terrestrial planet, telluric planet or rocky planet is a Planet that is primarily composed of Silicate rocks Within our In size and mass, it is very similar to the Earth, and is often described as its 'sister'. The diameter of Venus is only 650 km less than the Earth's, and its mass is 81. 5% of the Earth's. However, conditions on the Venusian surface differ radically from those on Earth, due to its dense carbon dioxide atmosphere. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single An atmosphere (from Greek ατμός - atmos, " Vapor " + σφαίρα - sphaira, " Sphere " The mass of the atmosphere of Venus is 96. 5% carbon dioxide, with most of the remaining 3. 5% composed of nitrogen. Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 [6]

### Internal structure

Though there is little direct information about its internal structure, the similarity in size and density between Venus and Earth suggests that it has a similar internal structure: a core, mantle, and crust. The planetary core consists of the innermost layer(s of a Planet. The mantle is a part of an Astronomical object. The interior of the Earth, similar to the other Terrestrial planets, is Chemically divided In Geology, a crust is the outermost solid shell of a planet or moon Like that of Earth, the Venusian core is at least partially liquid. 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 on Venus, likely due to the dry surface and mantle. Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere 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. In Physics, a magnetic field is a Vector field that permeates space and which can exert a magnetic force on moving Electric charges [7]

### Geography

About 80% of Venus's surface consists of smooth volcanic 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. A continent is one of several large Landmasses on Earth. They are generally identified by Convention rather than any strict criteria with seven regions The northern continent is called Ishtar Terra, after Ishtar, the Babylonian goddess of love, and is about the size of Australia. Ishtar Terra is one of two main highland regions on the Planet Venus. Ishtar ( D IŠTAR 𒀭𒌋𒁯 is the Assyrian and Babylonian counterpart to the Sumerian Inanna and to Babylon was a City-state of ancient Mesopotamia, the remains of which can be found in present-day Al Hillah, Babil Province, Iraq For a topic outline on this subject see List of basic Australia topics. Maxwell Montes, the highest mountain on Venus, lies on Ishtar Terra. Maxwell Montes is a Mountain Massif on the planet Venus, part of which contains the highest point on the planet's surface Its peak is 11 km above Venus's average surface elevation. The southern continent is called Aphrodite Terra, after the Greek goddess of love, and is the larger of the two highland regions at roughly the size of South America. Greek mythology is the body of stories belonging to the ancient Greeks concerning their gods and Heroes the nature of the world and the origins and significance South America is a Continent of the Americas, situated entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a Much of this continent is covered by a network of fractures and faults. [8]

As well as the impact craters, mountains, and valleys commonly found on rocky planets, Venus has a number of unique surface features. 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 larger body Among these are flat-topped volcanic features called farra, which look somewhat like pancakes and range in size from 20–50 km across, and 100–1000 m high; radial, star-like fracture systems called novae; features with both radial and concentric fractures resembling spiders' webs, known as arachnoids; and coronae, circular rings of fractures sometimes surrounded by a depression. In Astrogeology, an arachnoid is a large structure of unknown origin and they have been found only on the surface of the Planet Venus. All of these features are volcanic in origin. [9]

Almost all Venusian surface features are named after historical and mythological women. [10] The only exceptions are Maxwell Montes, named after James Clerk Maxwell, and two highland regions, Alpha Regio and Beta Regio. James Clerk Maxwell (13 June 1831 &ndash 5 November 1879 was a Scottish mathematician and theoretical physicist. Alpha Regio is a region of the planet Venus extending for about 1500 kilometers centered at 22°S 5°E Beta Regio is a region of the planet Venus known as a volcanic rise. These three features were named before the current system was adopted by the International Astronomical Union, the body that oversees planetary nomenclature. [11]

Cartesian coordinates of physical features on Venus are expressed relative to its prime meridian, defined as the line of longitude passing through a radar-bright spot at the center of the oval feature Eve, which lies to the south of Alpha Regio. The Prime Meridian is the meridian (line of Longitude) at which longitude is defined to be 0° [12][13]

### Surface geology

Main article: Geology of Venus
Map of Venus, showing the elevated 'continents' in yellow: Ishtar Terra at the top and Aphrodite Terra just below the equator to the right

Much of Venus's surface appears to have been shaped by volcanic activity. Venus has striking surface characteristics which are as beautiful as they are unusual Overall, Venus has several times as many volcanoes as Earth, and it possesses some 167 giant volcanoes that are over 100 km across. The only volcanic complex of this size on Earth is the Big Island of Hawaii. The Island of Hawaii, also called the Big Island or Hawaii Island, is a volcanic Island in the U The State of Hawaii ( or həˈwaɪʔiː Hawaiian: Mokuāina o Hawaii) is a state in the United States located on an Archipelago in the [9] However, this is not because Venus is more volcanically active than Earth, but because its crust is older. Earth's crust is continually recycled by subduction at the boundaries of tectonic plates, and has an average age of about 100 million years, while Venus's surface is estimated to be about 500 million years old. In Geology, a subduction zone is an area on Earth where two tectonic plates meet and move towards one another with one sliding underneath the other Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere [9]

Several lines of evidence point to ongoing volcanic activity on Venus. During the Soviet Venera program, the Venera 11 and Venera 12 probes detected a constant stream of lightning, and Venera 12 recorded a powerful clap of thunder soon after it landed. The Venera (Венера series of probes was developed by the USSR between 1961 and 1984 to gather data from Venus. The Venera 11 (Венера-11 was an USSR Unmanned space mission part of the Venera program to explore the planet Venus. The Venera 12 (Венера-12 was an USSR Unmanned space mission to explore the planet Venus. Lightning is an atmospheric discharge of Electricity, which typically occurs during Thunderstorms and sometimes during volcanic eruptions or Thunder is the sound made by Lightning. Depending on the nature of the lightning and distance of the listener it can range from a sharp The European Space Agency's Venus Express recorded abundant lightning in the high atmosphere. Venus Express is the first Venus exploration mission of the European Space Agency. [14] While rainfall drives thunderstorms on Earth, there is no rainfall on the surface of Venus (though it does rain sulfuric acid 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. Rain is Liquid precipitation. On Earth it is the condensation of atmospheric Water vapor into drops heavy enough to fall often making it to Sulfuric (or sulphuric acid, H 2 S[[oxygen O]]4 is a strong Mineral acid. Another intriguing 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. [15]

Impact craters on the surface of Venus (image reconstructed from radar data)

There are almost 1,000 impact craters on Venus, more or less evenly distributed across its surface. On other cratered bodies, such as the Earth and the Moon, craters show a range of states of erosion, indicating a continual process of degradation. On the Moon, degradation is caused by subsequent impacts, while on Earth, it is caused by wind and rain erosion. However, 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 total resurfacing event about 500 million years ago. [16] 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. [9]

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 are slowed down so much by the atmosphere that they do not create an impact crater. The kinetic energy of an object is the extra Energy which it possesses due to its motion [17]

### Atmosphere

Main article: Atmosphere of Venus

Venus has an extremely thick atmosphere, which consists mainly of carbon dioxide and a small amount of nitrogen. Structure and composition Composition The atmosphere of Venus is composed mainly of Carbon dioxide, along with a small amount of Nitrogen and other An atmosphere (from Greek ατμός - atmos, " Vapor " + σφαίρα - sphaira, " Sphere " Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 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 oceans. An ocean (from Greek, ''Okeanos'' (Oceanus) is a major body of saline water, and a principal component of the Hydrosphere. The density at the surface is 65 kg/m³ (6. 5% that of water). The enormously CO2-rich atmosphere, along with thick clouds of sulfur dioxide, generates the strongest greenhouse effect in the solar system, creating surface temperatures of over 460 °C. The Greenhouse effect refers to the change in the Thermal equilibrium temperature of a planet or moon by the presence of an Atmosphere containing gas that absorbs [18] This makes Venus's surface much hotter than Mercury'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 receives only 25% of Mercury's solar irradiance. Irradiance, radiant emittance, and radiant exitance are Radiometry terms for the power of Electromagnetic radiation at a surface per unit Because of the lack of any moisture on Venus, there is almost no relative humidity (no more than 1%) on the surface, creating a heat index of 450 °C to 480 °C.

Cloud structure in Venus's atmosphere, revealed by ultraviolet observations

Studies have suggested that several billion years ago Venus's 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 was caused by the evaporation of that original water, which generated a critical level of greenhouse gases in its atmosphere. [19] Thermal inertia and the transfer of heat by winds in the lower atmosphere mean that the temperature of Venus's surface does not vary significantly between the night and day sides, despite the planet's extremely slow rotation. Volumetric heat capacity ( VHC) describes the ability of a given Volume of a substance to store Internal energy while undergoing a given Temperature Winds at the surface are slow, moving at a few kilometers per hour, but because of the high density of the atmosphere at Venus's 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 were not a problem. [20] Above the dense CO2 layer are thick clouds consisting mainly of sulfur dioxide and sulfuric acid droplets. Sulfuric (or sulphuric acid, H 2 S[[oxygen O]]4 is a strong Mineral acid. [21][22] These clouds reflect about 60% of the sunlight that falls on them back into space, and prevent the direct observation of Venus's 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. In the absence of the greenhouse effect caused by the carbon dioxide in the atmosphere, the temperature at the surface of Venus would be quite similar to that on Earth. Strong 300 km/h winds at the cloud tops circle the planet about every four to five earth days. [23]

In 2007 the Venus Express probe discovered that a huge double atmospheric vortex exists at the south pole of the planet. The polar vortex is a persistent large-scale Cyclone located near the Earth's Poles, in the middle and upper Troposphere and the Stratosphere [24][25]

#### Climate

The surface of Venus is effectively isothermal; it retains a constant temperature between day and night and between the equator and the poles. An isothermal process is a Thermodynamic process in which the Temperature of the System stays Constant: &Delta T = 0 [1][26] The planet's minute axial tilt (less than three degrees, compared with 23 degrees for Earth), also minimizes seasonal temperature variation. In Astronomy, axial tilt is the Inclination angle of a planet's rotational axis in relation to its orbital plane. A season is one of the major divisions of the Year, generally based on yearly periodic changes in Weather. [27] The only appreciable variation in temperature occurs with altitude. In 1995, the Magellan probe imaged a highly reflective substance at the tops of Venus's highest mountain peaks which bore a strong resemblance to terrestrial snow. The Magellan spacecraft was a space probe sent to the planet Venus, the first post- Voyager unmanned spacecraft to be launched by NASA "Snowfall" redirects here For other uses see Snow (disambiguation or Snowfall (disambiguation. 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). Tellurium (tɪˈlʊəriəm/ /tɛl- is a Chemical element that has the symbol Te and Atomic number 52 Galena is the natural mineral form of Lead sulfide. It is the most important Lead Ore mineral [28]

The clouds of Venus are capable of producing lightning much like the clouds on Earth. Lightning is an atmospheric discharge of Electricity, which typically occurs during Thunderstorms and sometimes during volcanic eruptions or [29] The existence of lightning had been controversial since the first suspected bursts were detected by the Soviet Venera probes. However in 2006–2007 Venus Express clearly detected whistler mode waves, the signatures of lightning. Venus Express is the first Venus exploration mission of the European Space Agency. An electromagnetic electron wave is a wave in a plasma which has a Magnetic field component and in which primarily the Electrons oscillate Their intermittent appearance indicates a pattern associated with weather activity. In Dynamical systems intermittency is the alternation of phases of apparently periodic and chaotic dynamics The lightning rate is at least half of that on Earth. [29]

### Magnetic field and core

In 1980, The Pioneer Venus Orbiter found that Venus's magnetic field is both weaker and smaller (i. The Pioneer mission to Venus consisted of two components launched separately In Physics, a magnetic field is a Vector field that permeates space and which can exert a magnetic force on moving Electric charges e. closer to the planet) than Earth's. What small magnetic field is present is induced by an interaction between the ionosphere and the solar wind,[30] rather than by an internal dynamo in the core like the one inside the Earth. The ionosphere is the uppermost part of the atmosphere, distinguished because it is Ionized by solar radiation The solar wind is a Stream of charged particles&mdasha plasma &mdashthat are ejected from the upper atmosphere of the Sun. The dynamo theory proposes a mechanism by which a celestial body such as the Earth generates a Magnetic field. The planetary core consists of the innermost layer(s of a Planet. Venus's magnetosphere is too weak to protect the atmosphere from cosmic radiation. A magnetosphere' is a highly magnetized region around and possessed by an Astronomical object.

This lack of an intrinsic magnetic field at Venus was surprising given that it is similar to Earth in size, and was expected to also contain a dynamo in its core. A dynamo requires three things: a conducting liquid, rotation, and convection. In Science and engineering, a conductor is a material which contains movable Electric charges. Convection in the most general terms refers to the movement of molecules within Fluids (i The core is thought to be electrically conductive, however. Also, while its rotation is often thought to be too slow, simulations show that it is quite adequate to produce a dynamo. [31][32] This implies that the dynamo is missing because of a lack of convection in Venus's core. On Earth, convection occurs in the liquid outer layer of the core because the bottom of the liquid layer is much hotter than the top. Since Venus has no plate tectonics to let off heat, it is possible that it has no solid inner core, or that its core is not currently cooling, so that the entire liquid part of the core is at approximately the same temperature. Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere Another possibility is that its core has already completely solidified.

## Orbit and rotation

Size comparison of terrestrial planets (left to right): Mercury, Venus, Earth, and Mars

Venus orbits the Sun at an average distance of about 108 million km, and completes an orbit every 224. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 65 days. Although all planetary orbits are elliptical, Venus is the closest to circular, with an eccentricity of less than 0. In Physics, an orbit is the gravitationally curved path of one object around a point or another body for example the gravitational orbit of a planet around a star In Mathematics, an ellipse (from the Greek ἔλλειψις literally absence) is a Conic section, the locus of points in a Circles are simple Shapes of Euclidean geometry consisting of those points in a plane which are at a constant Distance, called the In Astrodynamics, under standard assumptions, any Orbit must be of Conic section shape 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 a distance of about 41 million km. [1] The planet reaches inferior conjunction every 584 days, on average. [1]

Venus rotates once every 243 days—by far the slowest rotation period of any of the major planets. A Venusian sidereal day thus lasts more than a Venusian year (243 versus 224. Sidereal time is a measure of the position of the Earth in its rotation around its axis or time measured by the apparent Diurnal motion of the Vernal equinox 7 Earth days). However, the length of a solar day on Venus is significantly shorter than the sidereal day; to an observer on the surface of Venus the time from one sunrise to the next would be 116. Solar times are measures of the apparent position of the Sun on the Celestial sphere. 75 days. [33] The Sun would appear to rise in the west and set in the east. At the equator, Venus's surface rotates at 6. 5 km/h; on Earth, the rotation speed at the equator is about 1,600 km/h.

If viewed from above the Sun's north pole, all of the planets are orbiting in a counter-clockwise direction; but while most planets also rotate counter-clockwise, Venus rotates clockwise in "retrograde" rotation. Direct motion is the motion of a Planetary body in a direction similar to that of other bodies within its system and is sometimes called prograde motion. The question of how Venus came to have a slow, retrograde rotation was a major puzzle for scientists when the planet's rotation period was first measured. When it formed from the solar nebula, Venus would have had a much faster, prograde rotation, but calculations show that over billions of years, tidal effects on its dense atmosphere could have slowed down its initial rotation to the value seen today. The formation and evolution of the Solar System is estimated to have begun Characteristics A tide is a repeated cycle of sea level changes in the following stages Over several hours the water rises or advances up a beach in the flood [34][35]

A curious aspect of Venus's 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 some kind of tidal locking with the Earth, is unknown. A separate article treats the phenomenon of Tidal resonance in Oceanography. [36]

Venus is currently moonless, though the asteroid 2002 VE68 presently maintains a quasi-orbital relationship with it. Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but 2002 VE68 (also written 2002 VE68) is an Asteroid discovered on November 11 2002. A quasi-satellite is an object in a 11 Orbital resonance with its Planet that stays close to the planet over many orbital periods [37] According to Alex Alemi and David Stevenson of the California Institute of Technology, their recent study of models of the early solar system shows that it is very likely that, billions of years ago, Venus had at least one moon, created by a huge impact event. The California Institute of Technology (commonly referred to as Caltech) is a private, Coeducational research university located in Pasadena See also Impact crater An impact event is the Collision of a large Meteoroid, Asteroid or Comet (generically [38][39] About 10 million years later, according to Alemi and Stevenson, another impact reversed the planet's spin direction. The reversed spin direction caused the Venusian moon to gradually spiral inward[40] until it collided and merged with Venus. Tidal acceleration is an effect of the Tidal forces between an orbiting Natural satellite ( i If later impacts created moons, those moons also were absorbed the same way the first one was. The Alemi/Stevenson study is recent, and it remains to be seen what sort of acceptance it will achieve in the scientific community.

## Observation

Venus as the Evening Star, next to a crescent moon
Successive inferior conjunctions of Venus occur about 1. Conjunction is a term used in Positional astronomy and Astrology. 6 Earth years apart and create a pattern of precessing pentagrams, due to a near 13:8 orbital resonance (the Earth orbits nearly 8 times for every 13 orbits of Venus). Precession refers to a change in the direction of the axis of a rotating object Early history Sumer The first known uses of the pentagram are found in Mesopotamian writings dating to about 3000 BC In Celestial mechanics, an orbital resonance occurs when two Orbiting bodies exert a regular periodic gravitational influence on each other usually due to their

Venus is always brighter than the brightest stars, with its apparent magnitude ranging from −3. The apparent magnitude ( m) of a celestial body is a measure of its Brightness as seen by an observer on Earth, normalized to the value 8 to −4. 6. This is bright enough to be seen even in the middle of the day, 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. The terms " inferior planet " and " superior planet " were originally used in the Ptolemaic Cosmology to differentiate those planets The Sun (Sol is the Star at the center of the Solar System. [41]

Venus 'overtakes' the Earth every 584 days as it orbits the Sun. [1] As it does so, it goes from being the 'Evening star', visible after sunset, to being the 'Morning star', visible before sunrise. While Mercury, the other inferior planet, reaches a maximum elongation of only 28° and is often difficult to discern in twilight, Venus is hard to miss when it is at its brightest. (For other uses of elongation see Elongation) Elongation is an Astronomical term that refers to the angle between the Sun and a planet 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'. U.S. President Jimmy Carter reported having seen a UFO in 1969, which later analysis suggested was probably the planet, and countless other people have mistaken Venus for something more exotic. The President of the United States is the Head of state and Head of government of the United States and is the highest political official in United States by James Earl "Jimmy" Carter Jr (born October 1 1924 was the thirty-ninth President of the United States, serving from 1977 to 1981 and the recipient of the 2002 The Jimmy Carter UFO Incident is the name given to an incident in which future US President Jimmy Carter reported seeing an Unidentified flying object while [42]

As it moves around its orbit, Venus displays phases like those of the Moon: it is new when it passes between the Earth and the Sun, full when it is on the opposite side of the Sun, and a half-phase when it is at its maximum elongations from the Sun. Planetary phase is the term used to describe the appearance of the illuminated section of a Planet. Venus is brightest when it is a thin crescent; it is much closer to Earth when a thin crescent than when gibbous, or full. Lunar phase (or Moon phase refers to the appearance of the illuminated portion of the Moon as seen by an observer usually on Earth [41]

Venus's 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. However, transits of Venus do occur in pairs separated by eight years, at intervals of about 120 years, when the planet's inferior conjunction coincides with its presence in the plane of the Earth's orbit. A transit of Venus across the Sun takes place when the Planet Venus passes directly between the Sun and Earth, obscuring a small portion of the Conjunction is a term used in Positional astronomy and Astrology. The most recent transit was in 2004; the next will be in 2012. Historically, transits of Venus were important, because they allowed astronomers to directly determine the size of the astronomical unit, and hence of the solar system. The astronomical unit ( AU or au or au or sometimes ua) is a unit of Length based on the distance from the Earth to the Captain Cook's exploration of the east coast of Australia came after he had sailed to Tahiti in 1768 to observe a transit of Venus. Captain James Cook FRS RN ( – 14 February 1779) was an English Explorer, Navigator and Tahiti is the largest Island in the Windward group of French Polynesia, located in the Archipelago of Society Islands in the [43][44]

A long-standing mystery of Venus observations is the so-called Ashen light—an apparent weak illumination of the dark side of the planet, seen when the planet is in the crescent phase. Ashen Light was first sighted by the astronomer Giovanni Battista Riccioli on January 9 1643, it is a subtle glow that is seen from the night side of the 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. [45]

## Studies of Venus

### Early studies

Galileo's discovery that Venus showed phases proved that it orbits the Sun and not the Earth

Venus was known in the Hindu Jyotisha since early times as the planet Shukra. Sharjah ( Arabic: الشارقة,, pronounced /'ʃɑɹdʒə/ in English) is one of the emirates of the United Arab Emirates (UAE Events 618 - Coronation of the Chinese governor Li Yuan as Emperor Gaozu of Tang, the new Emperor of China, initiating three centuries Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Jyotiṣa ( Sanskrit jyotiṣa, from jyótis- "light heavenly body" also spelled Jyotish and Jyotisha in English Graha (from Sanskrit ग्रह gráha -- seizing laying hold of holding is a 'cosmic influencer' on the living beings of mother Bhumidevi ( Earth) Shukra (शुक्र the Sanskrit for "clear pure" or "brightness clearness" is the name the son of Bhrgu and Urjaswathi In the West, before the advent of the telescope, Venus was known only as a 'wandering star'. A telescope is an instrument designed for the observation of remote objects and the collection of Electromagnetic radiation. In Astronomy, the naked-eye planets are the five Planets of our Solar system that can be discerned with the Naked eye without much difficulty Several cultures historically held its appearances as a morning and evening star to be those of two separate bodies. Pythagoras is usually credited with recognizing in the sixth century BC that the morning and evening stars were a single body, though he thought that Venus orbited the Earth. "Pythagoras of Samos" redirects here For the Samian statuary of the same name see Pythagoras (sculptor. When Galileo first observed the planet in the early 17th century, he found that it showed phases like the Moon's, varying from crescent to gibbous to full and vice versa. Galileo Galilei (15 February 1564 &ndash 8 January 1642 was a Tuscan ( Italian) Physicist, Mathematician, Astronomer, and Philosopher Planetary phase is the term used to describe the appearance of the illuminated section of a Planet. This could be possible only if Venus orbited the Sun, and this was among the first observations to clearly contradict the Ptolemaic geocentric model that the solar system was concentric and centered on the Earth. In Astronomy, the geocentric model of the Universe is the superseded theory that the Earth is the center of the universe and other [46]

Venus's atmosphere was discovered as early as 1790 by Johann Schröter. Johann Hieronymus Schröter ( August 30 1745 &ndash August 29 1816) was a German Astronomer. 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 of sunlight in a dense atmosphere. Scattering is a general physical process whereby some forms of Radiation, such as Light, Sound or moving particles for example are forced to deviate from Later, 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. Conjunction is a term used in Positional astronomy and Astrology. [47] The atmosphere complicated efforts to determine a rotation period for the planet, and observers such as Giovanni Cassini and Schröter incorrectly estimated periods of about 24 hours from the motions of markings on the planet's apparent surface. Giovanni Domenico Cassini ( June 8, 1625 &ndash September 14, 1712) was an Italian Mathematician, Astronomer [48]

### Ground-based research

Little more was discovered about Venus until the 20th century. Its almost featureless disc gave no hint as to what its surface might be like, and it was only with the development of spectroscopic, radar and ultraviolet observations that more of its secrets were revealed. Astronomical spectroscopy is the technique of Spectroscopy used in Astronomy. Radar is a system that uses electromagnetic waves to identify the range altitude direction or speed of both moving and fixed objects such as Aircraft, ships Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays 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 radiation. Frank Elmore Ross ( April 2, 1874 &ndash September 21, 1960) was an American Astronomer and Physicist. Infrared ( IR) radiation is Electromagnetic radiation whose Wavelength is longer than that of Visible light, but shorter than that of He suggested that this was due to a very dense yellow lower atmosphere with high cirrus clouds above it. Cirrus clouds are characterized by thin wisplike strands often accompanied by tufts leading to their common (non-standard name of 'mare's tail' [49]

90% of the surface Venus appears to be recently solid basalt lava. Spectroscopic observations in the 1900s gave the first clues about Venus's rotation. Vesto Slipher tried to measure the Doppler shift of light from Venus, but found that he could not detect any rotation. Vesto Melvin Slipher ( November 11, 1875 &ndash November 8, 1969) was an American Astronomer. The Doppler effect (or Doppler shift) named after Christian Doppler, is the change in Frequency and Wavelength of a Wave for He surmised that the planet must have a much longer rotation period than had previously been thought. [50] 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. [51]

Radar observations in the 1970s revealed details of Venus's surface for the first time. Pulses of radio waves were beamed at the planet using the 300 m radio telescope at Arecibo Observatory, and the echoes revealed two highly reflective regions, designated the Alpha and Beta regions. The Arecibo Observatory is a very sensitive Radio telescope located approximately south-southwest from the town of Arecibo in Puerto Rico. The observations also revealed a bright region attributed to mountains, which was called Maxwell Montes. [52] These three features are now the only ones on Venus which do not have female names.

The best radar images obtainable from Earth revealed features no smaller than about 5 km across. More detailed exploration of the planet could only be carried out from space.

## Exploration of Venus

### Early efforts

Mariner 2, launched in 1962

The first robotic space probe mission to Venus, and the first to any planet, began on February 12, 1961 with the launch of the Venera 1 probe. The observations and explorations of Venus started around 1600 BC A robotic spacecraft is a Spacecraft with no humans on board that is usually under Telerobotic control A space probe is a scientific Space exploration mission in which a Robotic spacecraft leaves the Gravity well of Earth and approaches the Events 1429 - English Forces under Sir John Fastolf defend a supply convoy carrying rations to the army besieging Orleans from attack by the Year 1961 ( MCMLXI) was a Common year starting on Sunday (link will display full calendar of the Gregorian calendar. February 12 1961, 003436 UTC, the first planetary probe was launched to Venus by the Soviet Union. 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. The Venera (Венера series of probes was developed by the USSR between 1961 and 1984 to gather data from Venus. It was estimated to have passed within 100,000 km from Venus in mid-May. [53]

The United States exploration of Venus also started badly with the loss of the Mariner 1 probe on launch. The United States of America —commonly referred to as the Mariner 1 was the first spacecraft of the Mariner program. Launched on July 22, 1962 as a Venus flyby mission a range safety The subsequent Mariner 2 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. Mariner 2 (Mariner-Venus 1962 a space probe to Venus, was the first successful Spacecraft in the NASA Mariner program. In Astronautics and Aerospace engineering, the Hohmann transfer orbit is an Orbital maneuver using two engine impulses which under standard assumptions Events 1287 - St Lucia's flood: The Zuider Zee sea wall in the Netherlands collapses killing over 50000 people Year 1962 ( MCMLXII) was a Common year starting on Monday (the link is to a full 1962 calendar of the Gregorian calendar. Its microwave and infrared radiometers revealed that while Venus's 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. Microwaves are electromagnetic waves with Wavelengths ranging from 1 mm to 1 m or frequencies between 0 Infrared ( IR) radiation is Electromagnetic radiation whose Wavelength is longer than that of Visible light, but shorter than that of A radiometer is a device for measuring the radiant flux (power of Electromagnetic radiation. Mariner 2 also obtained improved estimates of Venus's mass and of the astronomical unit, but was unable to detect either a magnetic field or radiation belts. The astronomical unit ( AU or au or au or sometimes ua) is a unit of Length based on the distance from the Earth to the In Physics, a magnetic field is a Vector field that permeates space and which can exert a magnetic force on moving Electric charges The Van Allen radiation belt is a Torus of energetic Charged particles ( plasma) around Earth, held in place by Earth's Magnetic [54]

### Atmospheric entry

The Venera 3 probe crash-landed on Venus on March 1, 1966. Venera 3 ( Russian:Венера-3 was a Venera program Space probe that was built and launched by the Soviet Union to explore the surface of Events 86 BC - Lucius Cornelius Sulla, at the head of a Roman Republic army enters in Athens, removing the Tyrant Year 1966 ( MCMLXVI) was a Common year starting on Saturday (link will display full calendar of the 1966 Gregorian calendar. 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. [55] Venus's next encounter with an unmanned probe came on October 18, 1967 when Venera 4 successfully entered the atmosphere and deployed a number of science experiments. Events 1009 - The Church of the Holy Sepulchre, a Christian church in Jerusalem, is completely destroyed by the Fatimid Year 1967 ( MCMLXVII) was a Common year starting on Sunday (link will display full calendar of the 1967 Gregorian calendar. Venera 4 ( Russian:Венера-4 was a probe in the Soviet Venera program for the exploration of Venus. 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 at an altitude of 24. 96 km. [55]

Another probe arrived at Venus one day later on October 19, 1967 when Mariner 5 conducted a flyby at a distance of less than 4,000 km above the cloud tops. Events 202 BCE - The Battle of Zama results in the defeat of Carthage and Hannibal. Year 1967 ( MCMLXVII) was a Common year starting on Sunday (link will display full calendar of the 1967 Gregorian calendar. Mariner 5 (Mariner Venus '67 was a spacecraft of the Mariner program that carried a complement of experiments to probe Venus ' atmosphere by radio occultation Mariner 5 was originally built as backup for the Mars-bound Mariner 4, but when that mission was successful, the probe was refitted for a Venus mission. Mariner 4 (Mariner-Mars 1964 was the fourth in a series of spacecraft intended for planetary exploration in a flyby mode and performed the first successful A suite of instruments more sensitive than those on Mariner 2, in particular its radio occultation experiment, returned data on the composition, pressure and density of Venus's atmosphere. In Shia Islam The Occultation is a term used to designate the hidden state of the Imam of the Time. [56] 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 and Venera 6 five days apart in January 1969; they encountered Venus a day apart on May 16 and May 17 that year. Venera 5 (Венера-5 was a probe in the Soviet space program ''Venera'' for the exploration of Venus. Venera 6 ( Russian:Венера-6 was a Soviet Spacecraft, launched from a Tyazheliy Sputnik (69-002C on January 10 1969 Events 1204 - Baldwin IX Count of Flanders is crowned as the first Emperor of the Latin Empire. Events 1521 - Edward Stafford 3rd Duke of Buckingham, is executed for Treason. The probes were strengthened to improve their crush depth to 25 atmospheres and were equipped with smaller parachutes to achieve a faster descent. A submarine's depth ratings are a primary design parameter and measure of its ability Since then-current atmospheric models of Venus suggested a surface pressure of between 75 and 100 atmospheres, 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. [55]

### Surface science

Venera 7 represented a concerted 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 Venera 7 (Венера-7 was a Soviet Spacecraft part of the Venera series of probes to Venus. The module was pre-cooled prior to entry and equipped with a specially reefed parachute for a rapid 35-minute descent. 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 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. Events 533 - Byzantine general Belisarius defeats the Vandals, commanded by King Gelimer, at the Battle of Year 1970 ( MCMLXX) was a Common year starting on Thursday (link shows full calendar of the Gregorian calendar. Probably tilted onto its side, it returned a weak signal supplying temperature data for 23 minutes, the first telemetry received from the surface of another planet. Telemetry (synonymous with Telematics) is a Technology that allows the remote measurement and reporting of Information of interest to the system designer [55]

The Venera program continued with Venera 8 sending data from the surface for 50 minutes, and Venera 9 and Venera 10 sending the first images of the Venusian landscape. Venera 8 (Венера-8 was a probe in the Soviet Venera program for the exploration of Venus. Venera 9 (Венера-9 was a USSR Unmanned space mission to Venus. Venera 10 (Венера-10 was a USSR Unmanned space mission to Venus. The two landing sites presented very different visages 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-like rock slabs interspersed with weathered material. Basalt (bəˈsɔːlt ˈbeisɔːlt ˈbæsɔːlt is a common Extrusive Volcanic rock. Weathering is the decomposition of earth rocks, Soils and their Minerals through direct contact with the planet's Atmosphere. [57]

The Pioneer Venus orbiter

In the meantime, the United States had sent the Mariner 10 probe on a gravitational slingshot trajectory past Venus on its way to Mercury. Mariner 10 was a robotic Space probe launched on November 3, 1973 to fly by the planets Mercury and Venus. In Orbital mechanics and Aerospace engineering, a gravitational slingshot, gravity assist or swing-by is the use of the relative movement and On February 5, 1974, Mariner 10 passed within 5790 km of Venus, returning over 4,000 photographs as it did so. Events 1576 - Henry of Navarre converts to Roman Catholicism in order to ensure his right to the throne of France. Year 1974 ( MCMLXXIV) was a Common year starting on Tuesday (link will display full calendar of the 1974 Gregorian calendar. The images, the best then achieved, showed the planet to be almost featureless in visible light, but ultraviolet light revealed details in the clouds that had never been seen in Earth-bound observations. Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays [58]

The American Pioneer Venus project consisted of two separate missions. The Pioneer mission to Venus consisted of two components launched separately [59] 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. The Pioneer mission to Venus consisted of two components launched separately "December 4th" redirects here For the song by Jay-Z, see December 4th (song. Year 1978 ( MCMLXXVIII) was a Common year starting on Sunday (link displays the 1978 Gregorian calendar) Radar is a system that uses electromagnetic waves to identify the range altitude direction or speed of both moving and fixed objects such as Aircraft, ships The Pioneer Venus Multiprobe released a total of five probes which entered the atmosphere on December 9, 1978, returning data on its composition, winds and heat fluxes. The Pioneer mission to Venus consisted of two components launched separately Events 536 - Byzantine General Belisarius enters Rome while the Ostrogothic garrison peacefully leaves the city Year 1978 ( MCMLXXVIII) was a Common year starting on Sunday (link displays the 1978 Gregorian calendar)

Four more Venera lander missions took place over the next four years, with Venera 11 and Venera 12 detecting Venusian electrical storms;[60] and Venera 13 and Venera 14, landing four days apart on March 1 and March 5, 1982, returning the first color photographs of the surface. The Venera 11 (Венера-11 was an USSR Unmanned space mission part of the Venera program to explore the planet Venus. The Venera 12 (Венера-12 was an USSR Unmanned space mission to explore the planet Venus. " Electrical Storm " was the only single from U2 's second compilation album The Best of 1990–2000, and one of the two new songs recorded for Venera 13 (Венера-13 was a probe in the Soviet Venera program for the exploration of Venus. Venera 14 (Венера-14 was a probe in the Soviet Venera program for the exploration of Venus. Events 86 BC - Lucius Cornelius Sulla, at the head of a Roman Republic army enters in Athens, removing the Tyrant Events 363 - Roman Emperor Julian moves from Antioch with an army of 90000 to attack the Sassanid Empire, in a Year 1982 ( MCMLXXXII) was a Common year starting on Friday (link displays the 1982 Gregorian calendar) 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 spectrometer, and attempted to measure the compressibility of the soil with an impact probe. X-ray fluorescence (XRF is the emission of characteristic "secondary" (or fluorescent X-rays from a material that has been excited by bombarding with high-energy A spectrometer is an Optical instrument used to measure properties of Light over a specific portion of the Electromagnetic spectrum, typically used [60] Venera 14, though, had the misfortune to strike its own ejected camera lens cap and its probe failed to make contact with the soil. [60] The Venera program came to a close in October 1983 when Venera 15 and Venera 16 were placed in orbit to conduct mapping of the Venusian terrain with synthetic aperture radar. Venera 15 (Венера-15 was a Spacecraft sent to Venus by the Soviet Union. Venera 16 (Венера-16 was a Spacecraft sent to Venus by the Soviet Union. Synthetic-aperture radar (SAR is a form of Radar in which the highly-directional (and thus very large rotating antenna used by conventional radar is replaced with many low-directivity

The Soviet Union had not finished with Venus, and in 1985 it took advantage of the opportunity to combine missions to Venus and Comet Halley, which passed through the inner solar system that year. Halley's Comet, officially designated 1P/Halley and also referred to as Comet Halley after Edmond Halley, is a Comet that can be seen every En route to Halley, on June 11 and June 15, 1985 the two spacecraft of the Vega program each dropped a Venera-style probe (of which Vega 1's partially failed) and released a balloon-supported aerobot into the upper atmosphere. Events 1184 BC - Trojan War: Troy is sacked and burned according to the calculations of Eratosthenes. Events 763 BC - Assyrians record a Solar eclipse that will be used to fix the Chronology of Mesopotamian history Year 1985 ( MCMLXXXV) was a Common year starting on Tuesday (link displays 1985 Gregorian calendar) Vega program were a series of Venus missions which also took advantage of the appearance of Comet Halley in 1986 An aerobot is an aerial robot usually used in the context of an unmanned space probe While work has been done since the 1960s on robot " rovers quot to explore 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 cells. A convection cell is a phenomenon of Fluid dynamics that occurs in situations where there are Temperature differences within a body of Liquid or [61][62]

### Manned Venus flyby

Main article: Manned Venus Flyby

A manned Venus flyby mission, using Apollo program hardware, was proposed in the late 1960s. A manned Venus flyby was considered by NASA in the mid 1960s as part of the Apollo Applications Program, using hardware derived from the Apollo program [63] The mission was planned to launch in late October or early November of 1973, and would have used a Saturn V to send three men to fly past Venus in a flight lasting approximately one year. The Saturn V (pronounced 'Saturn Five' popularly known as the Moon Rocket was a multistage liquid-fuel expendable Rocket used by NASA 's The spacecraft would have passed approximately 5,000 kilometres from the surface of Venus about four months later.

Magellan topographical map of Venus

The United States' Magellan probe was launched on May 4, 1989 with a mission to map the surface of Venus with radar. The Magellan spacecraft was a space probe sent to the planet Venus, the first post- Voyager unmanned spacecraft to be launched by NASA The Magellan spacecraft was a space probe sent to the planet Venus, the first post- Voyager unmanned spacecraft to be launched by NASA Events 1256 - The Augustinian monastic order is constituted at the Lecceto Monastery when Pope Alexander IV Year 1989 ( MCMLXXXIX) was a Common year starting on Sunday (link displays 1989 Gregorian calendar) [11] 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 Venus's surface by radar and mapped 95% of its gravity field. The Magellan spacecraft was a space probe sent to the planet Venus, the first post- Voyager unmanned spacecraft to be launched by NASA In 1994, at the end of its mission, Magellan was deliberately sent to its destruction into the atmosphere of Venus in an effort to quantify its density. The Magellan spacecraft was a space probe sent to the planet Venus, the first post- Voyager unmanned spacecraft to be launched by NASA Venus was observed by the Galileo and Cassini 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. Galileo was an Unmanned spacecraft sent by NASA to study the Planet Jupiter and its moons Named after the Astronomer Cassini–Huygens is a joint NASA / ESA / ASI Robotic spacecraft mission currently studying the planet Saturn and its The Solar System consists of the Sun and those celestial objects bound to it by Gravity. The Magellan spacecraft was a space probe sent to the planet Venus, the first post- Voyager unmanned spacecraft to be launched by NASA

### Current and future missions

The Venus Express probe was designed and built by the European Space Agency. Venus Express is the first Venus exploration mission of the European Space Agency. The European Space Agency ( ESA) established in 1975 is an intergovernmental organisation dedicated to the exploration of space, currently with 17 member Launched on November 9, 2005 by a Russian Soyuz-Fregat rocket procured through Starsem, it successfully assumed a polar orbit around Venus on April 11, 2006. Events 694 - Egica, a king of the Visigoths of Hispania, accuses Jews of aiding Muslims sentencing all Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar. The Soyuz launch vehicle (Western designation A-2 is an Expendable launch system manufactured by TsSKB-Progress in Samara Russia. Starsem is a European Russian company that was created in 1996 to commercialise the Soyuz launcher. A polar orbit is an Orbit in which a Satellite passes above or nearly above both poles of the body (usually a planet such as the Earth, but possibly Events 491 - Flavius Anastasius becomes Byzantine Emperor, with the name of Anastasius I. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. [64] The probe is undertaking a detailed study of the Venusian atmosphere and clouds, and will also map the planet's plasma environment and surface characteristics, particularly temperatures. In Physics and Chemistry, plasma is an Ionized Gas, in which a certain proportion of Electrons are free rather than being bound Its mission is intended to last a nominal 500 Earth days, or around two Venusian years. [64] One of the first results emerging from Venus Express is the discovery that a huge double atmospheric vortex exists at the south pole of the planet. The polar vortex is a persistent large-scale Cyclone located near the Earth's Poles, in the middle and upper Troposphere and the Stratosphere [64]

NASA's MESSENGER mission to Mercury performed two flybys of Venus in October 2006 and June 2007, in order to slow its trajectory for an eventual orbital insertion of Mercury in 2011. The MErcury Surface Space ENvironment GEochemistry and Ranging ( MESSENGER) probe is a NASA Spacecraft, launched August 3, 2004 MESSENGER collected scientific data on both those flybys. [65] The European Space Agency (ESA) will also launch a mission to Mercury, called BepiColombo, which will perform two flybys of Venus in August 2013 before it reaches Mercury orbit in 2019. The European Space Agency ( ESA) established in 1975 is an intergovernmental organisation dedicated to the exploration of space, currently with 17 member BepiColombo is a joint Cornerstone mission of the European Space Agency (ESA and the Japan Aerospace Exploration Agency (JAXA to the planet Mercury [66]

Future dedicated missions to Venus are planned. Japan's aerospace body JAXA is planning to launch its Venus climate orbiter, the PLANET-C, in 2010. The, or JAXA, is Japan's national Aerospace agency JAXA was formed on October 1 2003 as an Independent Administrative Institution through the PLANET-C, also known as Venus Climate Orbiter (VCO is a planned Japanese Unmanned spacecraft to explore Venus. [67] Under its New Frontiers Program, NASA has proposed a lander mission called the Venus In-Situ Explorer to land on Venus to study surface conditions and investigate the elemental and mineralogical features of the regolith, equipped with a core sampler to drill into the surface to study pristine rock samples not weathered by the very harsh surface conditions of the planet. NASA 's New Frontiers program is a series of medium-cost (not to exceed 700 million USD highly focused scientific space missions The Venus In-Situ Explorer (VISE 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 Regolith ( Greek: "blanket rock" is a layer of loose Heterogeneous material covering solid rock. Other proposed Venus exploration concepts include rovers, balloons, and Venus airplane concepts. The observations and explorations of Venus started around 1600 BC An aerobot is an aerial robot usually used in the context of an unmanned space probe While work has been done since the 1960s on robot " rovers quot to explore

## Venus in human culture

### Historic understanding

The Maya Dresden Codex, which calculates Venus's appearances

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. Maya codices (singular Codex) are folding Books stemming from the Pre-Columbian Maya civilization, written in Maya hieroglyphic It is described in Babylonian cuneiformic texts such as the Venus tablet of Ammisaduqa, which relates observations that possibly date from 1600 BC. Babylon was a City-state of ancient Mesopotamia, the remains of which can be found in present-day Al Hillah, Babil Province, Iraq The Venus tablet of Ammisaduqa recovered from the library at Nineveh, is a 7th century BC cuneiform tablet that bears much older ( Bronze Age) [68] The Babylonians named the planet Ishtar (Sumerian Inanna), the personification of womanhood, and goddess of love. Ishtar ( D IŠTAR 𒀭𒌋𒁯 is the Assyrian and Babylonian counterpart to the Sumerian Inanna and to Mesopotamian mythology is the collective name given to Sumerian Akkadian Assyrian and Babylonian mythologies from the land between the Tigris Inanna ( D INANNA B153ellstpng|100x20px|INANNA]]) is the Sumerian goddess of sexual love fertility and warfare The Ancient Egyptians believed Venus to be two separate bodies and knew the morning star as Tioumoutiri and the evening star as Ouaiti. Ancient Egypt was an Ancient Civilization in eastern North Africa, concentrated along the lower reaches of the Nile River in what is now Likewise believing Venus to be two bodies, the Ancient Greeks called the morning star Φωσφόρος, Phosphoros (Latinized Phosphorus), the "Bringer of Light" or Ἐωσφόρος, Eosphoros (Latinized Eosphorus), the "Bringer of Dawn". The term ancient Greece refers to the period of Greek history lasting from the Greek Dark Ages ca Phosphorus, (ˈfɒsfərəs is the Chemical element that has the symbol P and Atomic number 15 In Greek mythology, Hesperus ( Greek grc Ἓσπερος Hesperos) (Roman equivalent Vesper cf The evening star they called Hesperos (Latinized Hesperus) (Ἓσπερος, the "star of the evening"), but by Hellenistic times, they realized the two were the same planet. In Greek mythology, Hesperus ( Greek grc Ἓσπερος Hesperos) (Roman equivalent Vesper cf This article focuses on the cultural aspects of the Hellenistic age for the historical aspects see Hellenistic period. Hesperos would be translated into Latin as Vesper and Phosphoros as Lucifer ("Light Bearer"), a poetic term later used to refer to the fallen angel cast out of heaven. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. Lucifer is a name frequently given to Satan in Christian belief [b] The Romans would later name the planet in honor of their goddess of love, Venus, whereas the Greeks used the name of her Greek counterpart, Aphrodite (Phoenician Astarte). Ancient Rome was a Civilization that grew out of a small agricultural community founded on the Italian Peninsula as early as the 10th century BC Venus was a major Roman Goddess principally associated with Love, Beauty and fertility, the equivalent of the Greek goddess Astarte (from Greek Ἀστάρτη ( Astártē) is the name of a Goddess as known from Northwestern Semitic regions cognate in name origin

To the Hebrews it was known as Noga ("shining"), Helel ("bright"), Ayeleth-ha-Shakhar ("deer of the dawn") and Kochav-ha-'Erev ("star of the evening"). Hebrews (or Hebertes, Eberites, Hebreians, " Habiru " or " Habiri " Hebrew: עברים

Venus was important to the Maya civilization, who developed a religious calendar based in part upon its motions, and held the motions of Venus to determine the propitious time for events such as war. The Maya civilization is a Mesoamerican Civilization, noted for the only known fully developed written language of the Pre-Columbian Americas The Maya calendar is a system of distinct Calendars and Almanacs used by the Maya civilization of Pre-Columbian Mesoamerica, and by 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. [69]

The Maasai people named the planet Kileken, and have an oral tradition about it called The Orphan Boy. The Maasai are an indigenous African Ethnic group of semi-nomadic people located in Kenya and northern Tanzania. Kileken (sometimes Kileghen) is the subject of a myth of the Maasai people concerning the planet Venus. Oral tradition, oral culture and oral lore is a way for a society to transmit history, literature, law and other Knowledges [70]

Venus is important in many Australian aboriginal cultures, such as that of the Yolngu people in Northern Australia. Australian Aboriginal astronomy is a name given to the Indigenous Australian cultural traditions of astronomical study The Yolngu gather after sunset to await the rising of Venus, which they call Barnumbirr. 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, and "sang" much of the country into life.

In western astrology, derived from its historical connotation with goddesses of femininity and love, Venus is held to influence those aspects of human life. Astrology (from Greek grc ἄστρον astron, "constellation star" and grc -λογία -logia) is a group of Systems In Indian Vedic astrology, Venus is known as Shukra, meaning "clear, pure" or "brightness, clearness" in Sanskrit. Jyotiṣa ( Sanskrit jyotiṣa, from jyótis- "light heavenly body" also spelled Jyotish and Jyotisha in English Shukra (शुक्र the Sanskrit for "clear pure" or "brightness clearness" is the name the son of Bhrgu and Urjaswathi Sanskrit (sa संस्कृता वाक् saṃskṛtā vāk, for short sa संस्कृतम् saṃskṛtam) is a historical One of the nine Navagraha, it is held to affect wealth, pleasure and reproduction; it was the son of Bhrgu and Ushana, preceptor of the Daityas, and guru of the Asuras. Graha (from Sanskrit ग्रह gráha -- seizing laying hold of holding is a 'cosmic influencer' on the living beings of mother Bhumidevi ( Earth) Maharishi Bhrigu was one of the seven great sages one of the Saptarshis in ancient India one of many Prajapatis (the facilitators of Creation created by Brahma Ushna (उशना or Yat (याट was a brave king in Yadava Vansh born after three generations of Maharaja Shashabindu, who was born after Early Chinese astronomers called the planet Tai-pe, or the "beautiful white one". Modern Chinese, Korean, Japanese and Vietnamese cultures refer to the planet literally as the gold star (Chinese: 金星), based on the Five elements. China ( Wade-Giles ( Mandarin) Chung¹kuo² is a cultural region, an ancient Civilization, and depending on perspective a National Korea is a geographic area composed of two sovereign countries a civilization and a former state situated on the Korean Peninsula in East Asia. For a topic outline on this subject see List of basic Japan topics. Vietnam (ˌviːɛtˈnɑːm Việt Nam) officially In traditional Chinese philosophy, natural phenomena can be classified into the Wu Xing ( or the Five Phases, usually translated as five elements, Lakotan spirituality refers to Venus as the daybreak star, and associates it with the last stage of life and wisdom. The Lakota (laˈkˣota (also Teton, Tetonwan) are a Native American tribe

The astronomical symbol for Venus is the same as that used in biology for the female sex: a circle with a small cross beneath. Astronomical symbols are symbols used to represent various Celestial objects theoretical constructs and observational events in Astronomy. Female (♀ is the Sex of an Organism, or a part of an organism which produces ova (egg cells An organism's sex is defined by the gametes it produces males produce male gametes (spermatozoa or Sperm) while females produce female gametes (ova or Egg cells; individual [71] The Venus symbol also represents femininity, and in Western alchemy stood for the metal copper. Alchemy a part of the Occult Tradition is both a philosophy and a practice with an ultimately unknown aim involving the improvement of the alchemist as well as the making of Copper (ˈkɒpɚ is a Chemical element with the symbol Cu (cuprum and Atomic number 29 [71] 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. [71][72]

Perhaps the strangest appearance of Venus in literature is as the harbinger of destruction in Immanuel Velikovsky's Worlds in Collision (1950). In this intensely controversial book, Velikovsky argued that ancient references to Venus indicated that the planet had played a role in catastrophic events in the solar system within the past few thousand years. Scientists rejected Velikovsky's wild hypothesis, though his books were popular for a number of years. [73]

### In fiction

Main article: Venus in fiction

Findings from the first missions to Venus showed the reality to be very different, and brought this particular genre to an end,[75] a passing which Brian Aldiss and Harry Harrison marked with their 1968 anthology Farewell Fantastic Venus. Brian Wilson Aldiss, '''OBE''', (born August 18, 1925 in East Dereham, Norfolk, England) is a prolific English For the radio personality see Harry Harrison (radio. Harry Harrison (born Henry Maxwell Dempsey, March 12 1925 Farewell Fantastic Venus is a Science fiction Anthology edited by Brian Aldiss and Harry Harrison. However, 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 is the (theoretical process of engineering the global environment of the planet Venus in such a way as to make it suitable for human habitation [76] Arthur C. Clarke's 1997 novel 3001: The Final Odyssey, for example, postulates humans lowering Venus's temperature by steering cometary fragments to impact its surface. Sir Arthur Charles Clarke, CBE (16 December 1917–19 March 2008 was a British Science fiction Author, Inventor, and 3001 The Final Odyssey ( 1997) is a Science fiction Novel by Arthur C A comet is a small Solar System body that orbits the Sun and when close enough to the Sun exhibits a visible coma (atmosphere or a tail — A terraformed Venus is the setting for a number of diverse works of fiction that have included Star Trek, Exosquad and the manga Venus Wars. The terraforming (literally "Earth-shaping" of a Planet, moon, or other body is the hypothetical process of deliberately modifying its Exosquad was an American Animated television series created by Will Meugniot and Universal Animation Studios as a response to is a 1989 Science fiction Anime Film. It is directed by Yoshikazu Yasuhiko, co-written by Yuichi Sasamoto and Yoshikazu

## Notes

1. ^ Goddesses such as Gaia and Terra were named after the Earth, and not vice versa. The colonization of Venus has been a subject of much speculation and many works of science fiction since before the dawn of Spaceflight, and is still much discussed EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001
2. ^ Jerome translated Septuagint heosphoros and Hebrew helel as lucifer, in Isaiah 14:12. Jerome (c 347 – September 30, 420) ( Latin: Eusebius Sophronius Hieronymus; Εὐσέβιος Σωφρόνιος Ἱερώνυμος The Septuagint (ˈsɛptuədʒɪnt or simply " LXX " is the Koine Greek version of the Hebrew Bible, translated in stages between the The Book of Isaiah ( Hebrew: Sefer Y'sha'yah ספר ישעיה is a book of the Bible traditionally attributed to the Prophet Isaiah, who lived

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