A global view of Venus made from a mosaic of radar images from the Magellan spacecraft, centred at 90 degrees longitude.

Radar image of the surface of Venus, centered at 180 degrees east longitude

Venus has striking surface characteristics, which are as beautiful as they are unusual. The majority of what we know today about its surface stems from radar observations, mainly images sent by the Magellan probe from August 16, 1990, until the end of its sixth orbital cycle in September 1994. Ninety-eight per cent of the planet's surface was mapped, twenty-two per cent of it in three-dimensional stereoscopic images. Image File history File links File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... This long range radar antenna (approximately 40m (130ft) in diameter) rotates on a track to observe activities near the horizon. ... Download high resolution version (1024x1024, 144 KB)Original Caption Released with Image: This global view of the surface of Venus is centered at 180 degrees east longitude. ... Download high resolution version (1024x1024, 144 KB)Original Caption Released with Image: This global view of the surface of Venus is centered at 180 degrees east longitude. ... This long range radar antenna (approximately 40m (130ft) in diameter) rotates on a track to observe activities near the horizon. ... Adjective Venusian or (rarely) Cytherean (*min temperature refers to cloud tops only) Atmospheric characteristics Atmospheric pressure 9. ... This long range radar antenna (approximately 40m (130ft) in diameter) rotates on a track to observe activities near the horizon. ... Magellan spacecraft at Kennedy Space Center The Magellan spacecraft carried out a mission from 1989-1994, orbiting Venus from 1990-1994. ... August 16 is the 228th day of the year (229th in leap years) in the Gregorian Calendar. ... This article is about the year. ... September is the ninth month of the year in the Gregorian Calendar and one of four Gregorian months with 30 days. ... 1994 (MCMXCIV) was a common year starting on Saturday of the Gregorian calendar, and was designated the International year of the Family. ... Stereoscopy, stereoscopic imaging or 3-D (three-dimensional) imaging is a technique to create the illusion of depth in a photograph, movie, or other two-dimensional image, by presenting a slightly different image to each eye. ...

The surface of Venus is covered by a dense atmosphere and presents clear evidence of violent volcanic activity in the past, including shield and composite volcanoes similar to those found on Earth. Atmosphere is the general name for a layer of gases that may surround a material body of sufficient mass. ... Mauna Kea, a shield volcano, on the Island of Hawai‘i with a light dusting of snow. ... View of Mount Rainier, a stratovolcano. ...

Relative to the Moon, Mars or Mercury, Venus has few small impact craters. This is a result of the planet's dense atmosphere, which burns up smaller meteorites. Venus does have more medium to large craters, but still not as many as the Moon or Mercury. Crust composition Oxygen 43% Silicon 21% Aluminium 10% Calcium 9% Iron 9% Magnesium 5% Titanium 2% Nickel 0. ... Amongst the findings from the Opportunity rover is the presence of hematite on Mars in the form of small spheres on the Meridiani Planum. ... Atmospheric characteristics Atmospheric pressure trace Potassium 31. ... This article is about impact craters, also known as meteor craters. ... A burst of meteors A meteor is the visible path of a meteoroid that enters the Earths (or another bodys) atmosphere, commonly called a shooting star or falling star. ...

Some other unusual characteristics of the planet include features called coronae (Latin for crowns, based on their appearance), tesserae, and other figures known as arachnoids, resembling a spider's web. Long rivers of lava have been discovered, as well as evidence of Eolian erosion and tectonic shifts which have played an essential role in making the surface of Venus as complex as it is today. This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... Latin is an ancient Indo-European language originally spoken in the region around Rome called Latium. ... Crown names several entities associated with monarchy: A crown (headgear), the headgear worn by a monarch, other high dignitaries, divinities etcetera. ... Venusian arachnoid In astrogeology, an arachnoid is a large structure of unknown origin that have been found only on the surface of Venus. ... Look up Lava, ‘A‘a, or Pāhoehoe in Wiktionary, the free dictionary Lava is molten rock that a volcano expels during an eruption. ... Eolian (or aeolian) processes pertain to the activity of the winds. ... Severe soil erosion in a wheat field near Washington State University, USA. Erosion is the displacement of solids (soil, mud, rock, and so forth) by the agents of wind, water, ice, movement in response to gravity, or living organisms (in the case of bioerosion). ... ...

Despite the fact that Venus is the planet closest to Earth (some 40 million kilometres at inferior conjunction), and is similar in size, the resemblance is superficial: no probe has been able to survive more than a few hours on its surface because the atmospheric pressure is some 90 times that of the Earth's. The temperature on the surface is around 450°C (842°F). This is mostly caused by the greenhouse effect created by an atmosphere composed mainly of carbon dioxide (96.5%). Earth, also known as Terra, and (mostly in the 19th century) Tellus, is the third-closest planet to the Sun. ... The greenhouse effect, first discovered by Joseph Fourier in 1824, is the process by which an atmosphere warms a planet. ... Carbon dioxide is an atmospheric gas comprised of one carbon and two oxygen atoms. ...

Ultraviolet surveys of Venus show a Y-shaped pattern of cloud formation near the equator indicating that the upper layers of the atmosphere circulate around the planet once every four days, suggesting the presence of winds of up to 500 km/h (311 mph). These winds exist at high altitudes, but the atmosphere at the surface is realtively calm, and images from the surface reveal no evidence of wind erosion.

Knowledge of the surface of Venus before Magellan

Main article: Exploration of Venus This article needs to be cleaned up to conform to a higher standard of quality. ...

After the Moon, Venus was the second object in the solar system to be explored by radar from the Earth. The first studies were carried out in 1961 at NASA's Goldstone Observatory, part of the Deep Space Network. At successive inferior conjunctions, Venus was observed both by Goldstone and the National Astronomy and Ionosphere Center in Arecibo. The studies carried out were similar to the earlier measurement of transits of the meridian, which had revealed in 1963 that the rotation of Venus was retrograde (it rotates in the opposite direction to that in which it orbits the Sun). The radar observations also allowed astronomers to determine that the rotation period of Venus was 243.1 days, and that its axis of rotation was almost perpendicular to its orbital plane. It was also established that the radius of the planet was 6,052 kilometres (3761 mi), some 70 kilometres (43 mi) less than the best previous figure obtained with terrestrial telescopes. Presentation of the solar system (not to scale) The solar system comprises our Sun and the retinue of celestial objects gravitationally bound to it. ... 1961 (MCMLXI) was a common year starting on Sunday (link will take you to calendar). ... NASA Logo Listen to this article · (info) This audio file was created from the revision dated 2005-09-01, and does not reflect subsequent edits to the article. ... The Goldstone Deep Space Communications Complex (GDSCC) —commonly called the Goldstone Observatory— is located in Californias Mojave Desert (USA). ... Deep Space Network (DSN) is an international network of radio antennas that supports interplanetary spacecraft missions, and radio and radar astronomy observations for the exploration of the solar system and the universe. ... Conjunction is a term used in positional astronomy and astrology. ... The Arecibo Observatory is located in Arecibo, Puerto Rico on the north coast of the island. ... Arecibo is a municipality in Puerto Rico named after the Taino Cacique Arasibo. ... This article is about the astronomical concept. ... Prograde motion is the rotational or orbital motion of a body in a direction similar to that of other bodies within a given system, and is sometimes called direct motion. ... In astronomy, a rotation period is the time an astronomical object takes to complete one revolution around its rotation axis. ... The axis of rotation of a rotating body is a line such that the distance between any point on the line and any point of the body remains constant under the rotation. ... The orbital plane of an object orbiting another is the geometrical plane in which the orbit is embedded. ... RADIUS (Remote Authentication Dial In User Service) is an AAA (authentication, authorization and accounting) protocol for applications such as network access or IP mobility. ...

Interest in the geological characteristics of Venus was stimulated by the refinement of imaging techniques between 1970 and 1985. Early radar observations suggested merely that the surface of Venus was more compacted than the dusty surface of the Moon. The first radar images taken from the Earth showed very bright (radar-reflective) highlands christened Alpha Regio, Beta Regio, and Maxwell Montes; improvements in radar techniques later achieved an image resolution of 1–2 kilometres. Astrogeologist and NASA astronaut Harrison Jack Schmitt collecting lunar samples during the Apollo 17 mission Astrogeology is a planetary science discipline concerned with the geology of the celestial bodies such as the planets and their moons, asteroids, comets, and meteorites. ... 1970 (MCMLXX) was a common year starting on Thursday. ... This article is about the year. ... Regio (pl. ... Maxwell Montes has the highest point on Planet Venus. ...

Since the beginning of the age of space exploration, Venus had been considered as a site for future landings. Launch windows occur every 19 months, and from 1962 to 1985, every window was utilized to launch reconnaissance probes. Space exploration is the physical exploration of outer-space objects and generally anything that involves the technologies, science, and politics regarding space endeavors. ... Launch window is a term used in aerospace to describe a time period in which a particular rocket must be launched. ... 1962 (MCMLXII) was a common year starting on Monday (link will take you to calendar). ... This article is about the year. ...

In 1962, Mariner 2 flew over Venus, becoming the first man-made object to visit another planet. In 1965, Venera 3 became the first space probe to actually land on another world, albeit a crash-landing. In 1967, Venera 4 became the first probe to send data from the interior of Venus's atmosphere, while Mariner 5 measured the strength of Venus's magnetic field at the same time. Finally, in 1970, Venera 7 made the first controlled landing on Venus. In 1974, Mariner 10 swung by Venus on its way to Mercury and took ultraviolet photographs of the clouds, revealing the extraordinarily high wind speeds in the Venusian atmosphere. Conceptual drawing Mariner 2 was the first successful spacecraft in the NASA Mariner program, which began by sending spacecraft to Venus. ... Venera 3 was a Venera program space probe that was built and launched by the Soviet Union to explore the surface of Venus. ... This article is about the spacecraft type. ... Venera 4 was a probe in the Soviet Venera program for the exploration of Venus. ... Mariner 5 was a spacecraft of the Mariner program that carried a complement of experiments to probe Venus atmosphere with radio waves, scan its brightness in ultraviolet light, and sample the solar particles and magnetic field fluctuations above the planet. ... Current flowing through a wire produces a magnetic field (M) around the wire. ... Venera 7 lander Diagram of Venera-7 Insignia on board of Venera-7 Profile of Venera-7 The Venera 7 (Russian: Венера-7) was launched as part of the Venera program by the Soviet Union on August 17, 1970. ... The Mariner 10 probe. ...

In 1975, Venera 9 transmitted the first images of the surface of Venus and made gamma ray observations of rocks at the landing site. Later in that same year, Venera 10 would send further images of the surface. 1975 (MCMLXXV) was a common year starting on Wednesday (the link is to a full 1975 calendar). ... Venera 9 was a USSR unmanned space mission to Venus. ... This article is about electromagnetic radiation. ... Venera 10 was a USSR unmanned space mission to Venus. ...

An image of Venus's surface taken by Venera 9. It is highly distorted—the white area in the corners is the sky.

In 1978, the Pioneer 12 probe (also known as Pioneer Venus 1 or Pioneer Venus Orbiter) circled Venus and completed the first altimetry and gravity maps of the planet, between 63 and 78 degrees of latitude. The altimetry data had an accuracy of 150 kilometers. Download high resolution version (996x252, 173 KB) Wikipedia does not have an article with this exact name. ... Download high resolution version (996x252, 173 KB) Wikipedia does not have an article with this exact name. ... 1978 (MCMLXXVIII) was a common year starting on Sunday (the link is to a full 1978 calendar). ... The Pioneer mission to Venus consisted of two components, launched separately: an Orbiter and a Multiprobe. ... An altimeter is an active instrument used to measure the altitude of an object above a fixed level. ... Gravity is the force of attraction between massive particles. ... Latitude, sometimes denoted by the Greek letter φ, gives the location of a place on Earth north or south of the Equator. ...

That same year, Pioneer Venus 2 launched four probes into Venus's atmosphere which determined, when combined with data from prior missions, that the surface temperature of the planet was approximately 460°C (860°F), and that the atmospheric pressure at the surface was 90 times that of Earth, confirming earlier radar observations. diurnal (daily) rhythm of air pressure in northern Germany (black curve is air pressure) Atmospheric pressure is the pressure above any area in the Earths atmosphere caused by the weight of air. ...

In 1981, the Soviet Venera 13 sent the first colour image of Venus's surface and analysed the X-ray fluorescence of an excavated soil sample. The probe operated for a record 127 minutes on the planet's hostile surface. Also in 1981, the Venera 14 lander detected possible seismic activity in the planet's crust. 1981 (MCMLXXXI) is a common year starting on Thursday of the Gregorian calendar. ... Venera 13 Soviet Venus lander Venera 13 and Venera 14 were a pair of identical probes in the Soviet Venera program for the exploration of Venus. ... X-ray fluorescence (XRF) is the phenomenon where a material is exposed to X-rays of relatively high energy, and as the X-ray (or photon) strikes an atom (or a molecule) in the sample, energy is absorbed by the atom. ... Venera 13 Soviet Venus lander Venera 13 and Venera 14 were a pair of identical probes in the Soviet Venera program for the exploration of Venus. ... Seismology (from the Greek seismos = earthquake and logos = word) is the scientific study of earthquakes and the movement of waves through the Earth. ... In geology, a crust is the outer layer of a planet, part of its lithosphere. ...

Color image taken from the surface of Venus by the Soviet Venera 13 lander

In 1983, the Venera 15 and 16 acquired more precise radar images and altimetry data for the northern latitudes of the planet. This was the first use of synthetic aperture radar on Venus. The images had a 1–2 kilometre (0.6–1.2 mile) resolution. The altimetry data obtained by the Venera missions had a resolution four times better than Pioneer's. Venera-15 and 16 returned images of far greater quality than earth-based radar images, showing relief and texture absent from range-doppler imaging. From a highly eccentric polar orbit, the spacecraft recorded survey strips from the north pole down to 30 degrees latitude, during a 16-minute pass. The remander of the 24-hour orbit permitted the transmission of the 8 megabytes of information. Venus rotates 1.48 degrees every 24 hours, allowing the entire polar cap to be scanned during the mission, from November 11 1983 to July 10, 1984. This collection of radio holograms were processed into image strips and maps by SIMD math co-processors on a computer at the Institute of Radio Engineering and Electronics in Moscow. Download high resolution version (918x385, 51 KB)Color image taken from the surface of Venus by the Soviet Venera 13 lander File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Download high resolution version (918x385, 51 KB)Color image taken from the surface of Venus by the Soviet Venera 13 lander File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... 1983 (MCMLXXXIII) is a common year starting on Saturday of the Gregorian calendar. ... Venera 15 and Venera 16 were two identical spacecraft sent to Venus by the Soviet Union. ... Venera 15 and Venera 16 were two identical spacecraft sent to Venus by the Soviet Union. ... The surface of Venus, as imaged by the Magellan probe using SAR Synthetic aperture radar (SAR) is a form of radar in which sophisticated post-processing of radar data is used to produce a very narrow effective beam. ...

From Venera-15 and 16, most of the basic geomorphology of Venus were discovered. Soviet geologists discovered that many objects identified as meteor crators previously were actually unusual volcanic features. The features of Coronas, Arachnoids, Tessera and genuine meteroite craters were identified for the first time. No evidence of plate tectonics was seen, and Soviet scientists argued with Americans about this until Magellan verified their theory, that the entire planet was missing any features of plate boundaries. The rarity of meteorite craters showed that the surface of Venus was surprisingly young, only about 100 million years old. This suggested intense volcanic activity and resurfacing.

In 1985, during the euphoria of Halley's comet, the Soviet Union launched two Vega probes to Venus. Vega 1 and 2 each sent an instrumented helium balloon to a height of 50 kilometres (31 mi) above the surface, allowing scientists to study the dynamics of the most active part of Venus's atmosphere. This article is about the year. ... Comet Halley as taken with the Halley Multicolor Camera on the ESA Giotto mission. ... The Vega mission was a Venus mission which also took advantage of the appearance of Comet Halley in 1986. ... Atmospheric dynamics is the study of the forces that result in the changing motions of air within the Earths atmosphere. ...

Magellan studies the geology of Venus

3D view of Venus's Eistla Regio produced from Magellan radar data.

Launched May 4, 1989 aboard the space shuttle Atlantis, the Magellan probe was first placed into low Earth orbit, before firing its upper stage motor to send it on a trajectory toward Venus. On August 10, Magellan arrived at Venus and began to take images with radar. Each day it made 7.3 Venus orbits, imaging a strip 17–28 kilometres (11–17 mi) wide and 70,000 kilometres (43,496 mi) long. Covering the whole planet required 1,800 strips, which were combined into a single mosaic image. Image File history File links Magellan 3D perspective of Venus surface in western Eistla Regio Image source: http://images. ... Image File history File links Magellan 3D perspective of Venus surface in western Eistla Regio Image source: http://images. ... May 4 is the 124th day of the year in the Gregorian calendar (125th in leap years). ... 1989 (MCMLXXXIX) is a common year starting on Sunday of the Gregorian calendar. ... Shuttle Orbiter Atlantis (NASA Orbiter Vehicle Designation: OV-104) is one of five NASA space shuttles. ... August 10 is the 222nd day of the year (223rd in leap years) in the Gregorian Calendar. ...

The first images of Venus were received on August 16, 1990, and routine mapping operations began on September 15, 1990. The first mapping cycle (Cycle 1) lasted 243 terrestrial days—the time it takes Venus to rotate on its own axis under the probe's orbital plane. Cycle 1 was completed successfully on May 15, 1991, mapping 84% of the Venusian surface. August 16 is the 228th day of the year (229th in leap years) in the Gregorian Calendar. ... This article is about the year. ... September 15 is the 258th day of the year (259th in leap years). ... This article is about the year. ... May 15 is the 135th day of the year in the Gregorian Calendar (136th in leap years). ... 1991 (MCMXCI) is a common year starting on Tuesday of the Gregorian calendar. ...

Cycle 2 began immediately afterwards and lasted until January 15, 1992. In each cycle, the probe was inclined at a different "look angle", producing stereoscopic data which enabled scientists to compile a three-dimensional map of the surface—a technique known as synthetic aperture radar. January 15 is the 15th day of the year in the Gregorian calendar. ... 1992 (MCMXCII) was a leap year starting on Wednesday. ... The surface of Venus, as imaged by the Magellan probe using SAR Synthetic aperture radar (SAR) is a form of radar in which sophisticated post-processing of radar data is used to produce a very narrow effective beam. ...

Cycle 3 was due to finish on September 14, 1992, but was terminated a day early due to problems with onboard equipment. In total, radar coverage of 98% of the surface of Venus was obtained, with 22% of the images in stereo. Magellan produced surface images of unprecedented clarity and coverage, which are still unsurpassed. September 14 is the 257th day of the year in the Gregorian calendar (258th in leap years). ... 1992 (MCMXCII) was a leap year starting on Wednesday. ...

Cycles 4, 5 and 6 were devoted to collecting gravimetric data, for which Magellan was aerobraked to its lowest possible stable orbit, with a periapsis or closest approach of 180 kilometres (112 mi). At the end of Cycle 6 its orbit was reduced further, entering the outer reaches of the atmosphere. After carrying out a few final experiments, Magellan successfully completed its mission on October 11, 1994, and was de-orbited to burn up in Venus's atmosphere. Gravimetry is the measurement of gravitational force, weight, or density. ... Aerobraking is an advanced interplanetary space navigation technique, whereby the velocity vector of a space vehicle is modified by interaction with a target bodys atmosphere. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... October 11 is the 284th day of the year (285th in Leap years). ... 1994 (MCMXCIV) was a common year starting on Saturday of the Gregorian calendar, and was designated the International year of the Family. ...

Topography

With the invention of the telescope, optical observations of Venus became possible, although it soon became apparent that its surface is permanently hidden by dense cloud. In 1643, Francesco Fontana was the first of several astronomers claiming to see dark markings on these clouds, while others even said that they could see part of the surface through holes in the clouds. Astronomers also claimed to have seen brilliant points in certain spots on the disk of the planet, suggesting an enormous mountain whose top was higher than the clouds. The most famous such observations were made by Johann Hieronymus Schröter, a respected observer and collaborator of William Herschel, who reported several sightings from 1789 onwards of a bright circular point of light near the southern terminator of Venus, thought to be reflected light from a very tall mountain range or peak, around 43 kilometres (28 mi) high. Herschel disputed these observations and held them to be attributable to imperfections in Schröter's telescope. Many other observers claimed to see irregularities in the terminator of Venus, and the debate continued into the 20th century until radar observations were able to penetrate the clouds and reveal that in fact, no such giant mountains exist (James, 2003). 50 cm refracting telescope at Nice Observatory. ... // Events January 21 - Abel Tasman discovers Tonga February 6 - Abel Tasman discovers the Fiji islands. ... Francesco Fontana (1585 or 1602 – 1656) was an Italian lawyer and astronomer. ... Johann Hieronymus Schröter (August 30, 1745 – August 29, 1816) was a German astronomer. ... Sir Wilhelm Friedrich Herschel, FRS (Hanover, November 15, 1738 – August 25, 1822 Slough, then in Buckinghamshire now in Berkshire) was a German-born British astronomer and composer who became famous for discovering the planet Uranus, and made many other astronomical discoveries. ... 1789 was a common year starting on Thursday (see link for calendar). ... A composite image showing the terminator crossing Europe and Africa The terminator is the line between the illuminated, day side and dark, night side of a planetary body (also known as the grey line). It is defined as the locus of points on a moon or planet where the line...

The reality is quite different: the surface of Venus is comparatively very flat. When 93% of the topography was mapped by Pioneer Venus, scientists found that the total distance from the lowest point to the highest point on the entire surface was about 13 kilometres (8 mi), while on the Earth the distance from the basins to the Himalayas is about 20 kilometres (12.4 mi). Surface of the Earth Topography, a term in geography, has come to refer to the lay of the land, or the physiogeographic characteristics of land in terms of elevation, slope, and orientation. ... An oceanic basin is anywhere on Earth that is covered by seawater. ... The Himalaya is a mountain range in Asia, separating the Indian subcontinent from the Tibetan Plateau. ...

According to the data of the altimeters of the Pioneer, nearly 51% of the surface is found located within 500 metres (1640 feet) of the median radius of 6,052 km (3760 mi); only 2% of the surface is located at greater elevations than 2 kilometres (1.2 mi) from the median radius. An altimeter is an active instrument used to measure the altitude of an object above a fixed level. ...

The altimetry experiment of Magellan confirmed the general character of the landscape. According the Magellan data, 80% of the topography is within 1 kilometre (0.6 mi) of the median radius. The most important elevations are in the mountain chains that surround Lakshmi Planum: Maxwell Montes (11 km, 6.8 mi), Akna Montes (7 km, 4.3 mi) and Freya Montes (7 km, 4.3 mi). Despite the relatively flat landscape of Venus, the altimetry data also found large inclined plains. Such is the case on the southwest side of Maxwell Montes, which in some parts seems to be inclined some 45°. Inclinations of 30° were registered in Danu Montes and Themis Regio.

Based on the altimeter data of the Pioneer Venus probe, the topography of the planet is divided into three topographical provinces: lowlands, deposition plains, and highlands. The Magellan data support these divisions. The most important provinces of the highlands are Aphrodite Terra, Ishtar Terra, and Lada Terra, as well as the regiones Beta, Phoebe and Themis. The regions Alpha, Bell, Eistla and Tholus form a less important group of highlands. Regio (pl. ...

Impact craters

Danilova crater in relief

Earth-based radar surveys made it possible to identify some topographic patterns related to craters, and the Venera 15 and 16 probes identified almost 150 such features of probable impact origin. Global coverage from Magellan subsequently made it possible to identify nearly 900 impact craters. Image File history File links Venus_Danilova_Aglaonice_Saskia_3D.gif Computer generated 3-dimensional perspective view of the crater farm on Venus, consisting of the 37. ... Image File history File links Venus_Danilova_Aglaonice_Saskia_3D.gif Computer generated 3-dimensional perspective view of the crater farm on Venus, consisting of the 37. ... This article is about impact craters, also known as meteor craters. ... Venera 15 and Venera 16 were two identical spacecraft sent to Venus by the Soviet Union. ...

Danilova, Aglaonice and Saskja craters

Crater counts give an important estimate for the age of the surface of a planet. Over time, bodies in the solar system are randomly impacted, so the more craters a surface has, the older it is. Compared to Mercury, the Moon and other such bodies, Venus has very few craters. In part, this is because Venus's dense atmosphere burns up smaller meteorites before they hit the surface. The Venera and Magellan data agree: there are very few impact craters with a diameter less than 30 kilometres (18 mi), and data from Magellan show an absence of any craters less than 2 kilometres (1.2 mi) in diameter. However, there are also fewer of the large craters, and those appear relatively young; they are rarely filled with lava, showing that they happened after volcanic activity in the area, and radar shows that they are rough and have not had time to be eroded down. Image File history File links RADAR pictures of craters on Venus, from the Spanish Wikipedia. ... Image File history File links RADAR pictures of craters on Venus, from the Spanish Wikipedia. ... Atmospheric characteristics Atmospheric pressure trace Potassium 31. ... Crust composition Oxygen 43% Silicon 21% Aluminium 10% Calcium 9% Iron 9% Magnesium 5% Titanium 2% Nickel 0. ... A burst of meteors A meteor is the visible path of a meteoroid that enters the Earths (or another bodys) atmosphere, commonly called a shooting star or falling star. ...

On older bodies such as the Moon, crater counts can also be used to look at the ages of different areas of the surface; on the Moon, there are more craters in the older hills. On Venus, there are few enough craters to make this analysis difficult. However, the surface is consistent with a completely random distribution, implying that the surface of the entire planet is roughly the same age, or at least that very large areas are not enormously different from the average.

Together, this evidence shows that the surface of Venus is young. The estimated age of the surface is ~650 million years, compared to more that 4 billion years for the age of the solar system. A young surface that was created all at the same time is different from any of the other terrestrial planets, and implies that there was some sort of global resurfacing event about 650 million years ago.

Global Resurfacing Event

It is theorized that Venus underwent some sort of global resurfacing about 650 million years ago, which is the approximate age of much of the surface of the planet. Although it is exciting to imagine the entire crust of Venus sinking into the mantle, it is probably more reasonable to discuss massive lava flows lasting thousands to millions of years.

One possible explanation for this event is that it is part of a cyclic process on Venus. On Earth, plate tectonics allow for the escape of heat from the mantle. However, Venus has no evidence for plate tectonics, so the theory is that the interior of the planet heats up (due to the decay of radioactive elements) until material in the mantle is hot enough to force its way to the surface. The subsequent resurfacing event covers most or all of the planet with lava, until the mantle is cool enough that the process starts over.

There are several other attributes of Venus that this model can help explain. Venus's lack of a magnetic field is puzzling, as Venus is similar to Earth in size, and presumably composition. However, it can be explained by a core that is not losing heat. Also, Venus has a much higher deuterium to hydrogen ratio in its atmosphere than Earth or comets do. Atmospheric escape is one of the very few processes that differentiate between the deuterium and hydrogen. The extremely high ratio implies that there were large amounts of water in Venus's atmosphere more recently than the beginning of the solar system, and a massive eruption would release large quantities of water (as well as other compounds, for example the sulfur that leads to the sulferic acid clouds of Venus). Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance of one atom in 6500 of hydrogen. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... There are several different processes that can lead to the escape of a planetary atmosphere. ...

More evidence is needed to put the theory of global resurfacing of Venus on firm ground. However, several different things support it, and it is hard to explain the crater pattern of Venus without something at least vaguely resembling this idea.

Volcanoes

Perspective view of pancake domes in Venus's Alpha Regio

Arachnoid surface feature on Venus

The surface of Venus is dominated by volcanism. Although Venus is superficially similar to Earth, it seems that the tectonic plates so active in Earth's geology do not exist on Venus. About 80% of the planet consists of a mosaic of volcanic lava plains, dotted with more than a hundred large isolated shield volcanoes, and many hundreds of smaller volcanoes and volcanic constructs such as coronae. These are geological features believed to be unique to Venus: huge, ring-shaped structures 100–300 kilometres (60–180 mi) across and rising hundreds of metres above the surface. It is believed that they are formed when plumes of rising hot material in the mantle push the crust upwards into a dome shape, which then collapses in the centre as the molten lava cools and leaks out at the sides, leaving a crown-like structure: the corona. Eruption redirects here. ... Image File history File links This is a composite image, dated 20 January 1998, of a Venusian arachnoid, built up from radar echoes from the Magellan spacecraft that orbited Venus from 1990 to 1994. ... Image File history File links This is a composite image, dated 20 January 1998, of a Venusian arachnoid, built up from radar echoes from the Magellan spacecraft that orbited Venus from 1990 to 1994. ... The tectonic plates of the world were mapped in the second half of the 20th century. ... Look up Lava, ‘A‘a, or Pāhoehoe in Wiktionary, the free dictionary Lava is molten rock that a volcano expels during an eruption. ... Mauna Kea, a shield volcano, on the Island of Hawai‘i with a light dusting of snow. ... This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... A Mantle is a piece of clothing, similar to a robe but open on the front side and often sleeveless. ...

Differences can be seen in volcanic deposits. In many cases, volcanic activity is localized to a fixed source, and deposits are found in the vicinity of this source. This kind of volcanism is called "centralized volcanism," in that volcanoes and other geographic features form distinct regions. The second type of volcanic activity is not radial or centralized; flood basalts cover wide expanses of the surface, similar to features such as the Deccan Traps on Earth. These eruptions are catalogued as "flow type" volcanoes. A flood basalt is a giant volcanic eruption that coats large stretches of land with basalt lava. ... The Deccan Traps is a large igneous province located in west-central India and is one of the largest volcanic features on Earth. ...

Volcanoes less than 20 kilometres (12 mi) in diameter are very abundant on Venus and they may number hundreds of thousands or even millions. Many appear as flattened domes or 'pancakes', thought to be formed in a similar way to shield volcanoes on Earth. These volcanoes are up to 15 kilometres (9 mi) in diameter and less than 1 kilometre (0.6 mi) in height. It is common to find groups of hundreds of these volcanoes in areas called shield fields. Mauna Kea, a shield volcano, on the Island of Hawai‘i with a light dusting of snow. ...

On Earth, volcanos are mainly of two types: shield volcanoes and composite or stratovolcanoes. The shield volcanoes, for example those in Hawaii, eject magma from the depths of the Earth in zones called hot spots. The lava from these volcanos is relatively fluid and permits the escape of gases. Composite volcanos, such as Mount Saint Helens and Mount Pinatubo, are associated with tectonic plates. In this type of volcano, the oceanic crust of one plate is sliding underneath the other in a subduction zone, together with an inflow of seawater, producing a gummier lava that restricts the exit of the gases, and for that reason, composite volcanoes tend to erupt more violently. Mauna Kea, a shield volcano, on the Island of Hawai‘i with a light dusting of snow. ... View of Mount Rainier, a stratovolcano. ... State nickname: The Aloha State Official languages Hawaiian and English Capital Honolulu Largest city Honolulu Governor Linda Lingle (R) Senators Daniel Inouye (D) Daniel Akaka (D) Area  - Total  - % water Ranked 43rd 28,337 km² 41. ... Magma is molten rock often located inside a magma chamber beneath the surface of the Earth. ... In geology, a hotspot is a location on the Earths surface that has experienced active volcanism for a long period of time. ... Mount St. ... Mount Pinatubo is an active volcano located on the island of Luzon in the Philippines, at the intersection of the borders of the provinces of Zambales, Bataan, and Pampanga. ... Age of oceanic crust Oceanic crust is the part of Earths lithosphere which underlies the ocean basins. ... Categories: Geology stubs | Plate tectonics ...

On Venus, where there are no tectonic plates or seawater, volcanoes are of the shield type. Nevertheless, the morphology of the volcanos of Venus is different: on the Earth, shield volcanoes can be a few tens of kilometres wide and up to 10 kilometres high (6.2 mi) in the case of Mauna Kea, measured from the sea floor. On Venus, these volcanos can cover hundreds of kilometres in area, but they are relatively flat, with an average height of 1.5 kilometres (0.9 mi). Mauna Kea is a dormant volcano in the Hawaiian Islands, one of five volcanic peaks that together form the Island of Hawaii. ...

The domes of Venus (commonly called pancake domes) are between 10 and 100 times larger than those formed on Earth. They are usually associated with coronae and tesserae (large regions of highly deformed terrain, folded and fractured in two or three dimensions, believed to be unique to Venus). The pancakes are thought to be formed by highly viscous, silica-rich lava erupting under Venus's high atmospheric pressure. In volcanology, a lava dome is mound-shaped growth resulting from the eruption of high-silica lava (such as rhyolite) from a volcano. ... The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. ...

Other unique features of Venus's surface are novae (radial networks of dikes or grabens) and arachnoids. A nova is formed when large quantities of magma are extruded onto the surface to form radiating ridges and trenches which are highly reflective to radar. These dikes form a symmetrical network around the central point where the lava emerged, where there may also be a depression caused by the collapse of the magma chamber. A dike in geology refers to a tabular intrusive igneous body. ... USGS image A graben is a depressed block of land bordered by parallel faults. ... Venusian arachnoid In astrogeology, an arachnoid is a large structure of unknown origin that have been found only on the surface of Venus. ... A magma chamber is the chamber beneath a volcano where the magma is held before an eruption. ...

Arachnoids are so named because they resemble a spider's web, featuring several concentric ovals surrounded by a complex network of radial fractures similar to those of a nova. It is not known whether the 250 or so features identified as arachnoids actually share a common origin, or are the result of different geological processes.

Tectonic activity

Despite the fact that Venus appears to have no tectonic plates as such, the planet's surface shows various features usually associated with tectonic activity. Features such as faults, folds, volcanoes, large mountains and rift valleys are caused on Earth by plates moving over the planet's molten interior. The tectonic plates of the world were mapped in the second half of the 20th century. ... The tectonic plates of the world were mapped in the second half of the 20th century. ... Old fault exposed by roadcut near Harrisburg, Pennsylvania. ... See also folding A fold in Slichowice nature reserve in Kielce (Variscan orogeny) The term fold is used in geology when one or a stack of originally flat and planar surfaces, such as sedimentary strata, are bent or curved as a result of plastic (i. ... Eruption redirects here. ...

The active volcanism of Venus has generated chains of folded mountains, rift valleys and terrain known as tesserae, a word meaning "floor tiles" in Greek. Tesserae exhibit the effects of eons of compression and tensional deformation.

Unlike those on Earth, the deformations on Venus are directly related to the dynamic forces within the planet's mantle. Gravitational studies suggest that Venus lacks an asthenosphere—a layer of lower viscosity that facilitates the movement of tectonic plates. The absence of this layer suggests that the deformation of Venus' surface can be explained by convective movements within the planet. A Mantle is a piece of clothing, similar to a robe but open on the front side and often sleeveless. ... Dont be afraid of big words. ... The pitch drop experiment at the University of Queensland. ... Convection is the transfer of heat by electric waves or by the motion within a fluid. ...

The tectonic deformations on Venus occur on a variety of scales, the smallest of which are related to linear fractures or faults. In many areas these faults appear as networks of parallel lines. Small, discontinuous mountain crests are found which resemble those on the Moon and Mars. The effects of extensive tectonism are shown by the presence of normal faults, where the crust has sunk in one area relative to the surrounding rock, and superficial fractures. Radar imaging shows that these types of deformation are concentrated in belts located in the equatorial zones and at high southern latitudes. These belts are hundreds of kilometres wide and they appear to interconnect across the whole of the planet, forming a global network associated with the distribution of volcanoes. Crust composition Oxygen 43% Silicon 21% Aluminium 10% Calcium 9% Iron 9% Magnesium 5% Titanium 2% Nickel 0. ... Mars is the fourth planet from the Sun in the solar system, named after the Roman god of war (the counterpart of the Greek Ares), on account of its blood red color as viewed in the night sky. ... Latitude, sometimes denoted by the Greek letter φ, gives the location of a place on Earth north or south of the Equator. ...

The rifts of Venus, formed by the expansion of the lithosphere, are groups of depressions tens to hundreds of metres wide and extending up to 1,000 kilometres in length. The rifts are mostly associated with large volcanic elevations in the form of domes, such as those at Beta Regio, Atla Regio and the western part of Eistla Regio. These highlands seem to be the result of enormous mantle plumes (rising currents of magma) which have caused elevation, fracturing, faulting, and volcanism. USGS image In geology, a rift is a place where the Earths crust and lithosphere are being pulled apart. ... The lithosphere (from the Greek for rocky sphere) is the solid outermost shell of a rocky planet. ... A mantle plume is a manifestation of a type of geological phenomenon originally proposed by W. Jason Morgan in 1971. ...

The highest mountain chain on Venus, Maxwell Montes in Ishtar Terra, was formed by a process of compression, expansion, and lateral movements. Another type of geographical feature, found in the lowlands, consists of ridge belts elevated several kilometres above the surface, hundreds of kilometres wide and thousands long. Two major concentrations of these belts exist: one in Lavinia Planitia near the southern pole, and the second adjacent to Atalanta Planitia near the northern pole. Maxwell Montes has the highest point on Planet Venus. ...

Tesserae are found mainly in Aphrodite Terra, Alpha Regio, Tellus Regio and the eastern part of Ishtar Terra (Fortuna Tessera). These regions contain the superimposition and intersection of grabens of different geological units, indicating that these are the oldest parts of the planet. It was once thought that the tesserae were continents associated with tectonic plates like those of the Earth; in reality they are probably the result of floods of basaltic lava forming large plains, which were then subjected to intense tectonic fracturing (Basilevsky, 2003). USGS image A graben is a depressed block of land bordered by parallel faults. ... Dymaxion map by Buckminster Fuller shows land mass with minimal distortion as only one continuous continent A continent (Latin continere, to hold together) is a large continuous mass of land on the planet Earth. ...

Magnetic field and structure

Cutaway diagram of possbile internal structure

Venus's crust appears to be 50 kilometres (31 mi) in thickness, and it is composed of silicious rocks. Venus's mantle is approximately 3,000 kilometres (1860 mi) thick, but its composition is unknown. Since Venus is a terrestrial planet, it is presumed to have a core made of semisolid iron and nickel with a radius of approximately 3,000 kilometres (1860 mi). Image File history File links InteriorOfVenus. ... Image File history File links InteriorOfVenus. ... The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. ... A Mantle is a piece of clothing, similar to a robe but open on the front side and often sleeveless. ... A Earths solar system has four terrestrial planets: Mercury, Venus, Earth and Mars. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ... General Name, Symbol, Number nickel, Ni, 28 Chemical series transition metals Group, Period, Block 10, 4, d Appearance lustrous, metallic Atomic mass 58. ... RADIUS (Remote Authentication Dial In User Service) is an AAA (authentication, authorization and accounting) protocol for applications such as network access or IP mobility. ...

The Pioneer Venus Orbiter found that Venus does not have a significant magnetic field. The magnetic field of a planet is produced by a dynamo in its core. A dynamo requires a conducting liquid, rotation, and convection. Venus is thought have a electically conductive core, and although its rotation period is very long (243.7 Earth days), simulations show that this is adaquate to produce a dynamo (Stevenson 2003). This implies that Venus lacks convection in its core. Convection occurs when there is a large difference in temperature between the inner and outer part of the core, but since Venus has no plate tectonics to let off heat, it is possible that it has no inner core, or that its core is not currently cooling. Current flowing through a wire produces a magnetic field (M) around the wire. ... Dynamo can refer to more than one item. ... Convection is the transfer of heat by electric waves or by the motion within a fluid. ...

Lava flows and channels

Lava flows near Ammavaru caldera

Lava flows on Venus are often much larger than Earth's, up to several hundred kilometres long and tens of kilometres wide. It is still unknown why these lava fields or lobate flows reach such sizes, but it is suggested that they are the result of very large eruptions of basaltic, low-viscosity lava spreading out to form wide, flat plains (Basilevsky, 2003). Image File history File links Download high resolution version (903x1106, 213 KB)Lava flows about 500km across on Venus originating from the Ammavaru caldera. ... Image File history File links Download high resolution version (903x1106, 213 KB)Lava flows about 500km across on Venus originating from the Ammavaru caldera. ...

On Earth, there are two known types of basaltic lava: ‘A‘a and Pāhoehoe. ‘A‘a lava presents a rough texture in the shape of broken blocks (clinkers). Pāhoehoe lava is recognized by its pillowy or ropy appearance. Rough surfaces appear brighter in radar images, which can be used to determine the differences between ‘A‘a and Pāhoehoe lavas. These variations can also reflect differences in lava age and preservation. Channels and lava tubes (channels that have cooled down and over which a dome has formed) are very common on Venus. Look up Lava, ‘A‘a, or Pāhoehoe in Wiktionary, the free dictionary Lava is molten rock that a volcano expels during an eruption. ... Look up Lava, ‘A‘a, or Pāhoehoe in Wiktionary, the free dictionary Lava is molten rock that a volcano expels during an eruption. ... Clinker has several meanings: In boat building, clinker is a method of constructing wooden boats by fixing planks to a frame so that the planks overlap each other gaining support from the frame and from adjacent planks. ... Lava tubes are natural conduits through which lava travels beneath the surface of a lava flow. ...

For the most part, lava flow fields are associated with volcanoes. The central volcanoes are surrounded by extensive flows that form the core of the volcano. They are also related to fissure craters, coronae, dense clusters of volcanic domes, cones, wells and channels.

Thanks to Magellan, more than 200 channels and valley complexes were identified. The channels were classified as simple, complex, or compound. Simple channels are characterized by a single, long main channel. This category includes rills similar to those found on the Moon, and a new type, called canali, consisting of long, distinct channels which maintain their width throughout their entire course. The longest such channel identified (Baltis Vallis) has a length of more than 6,800 kilometres (4,200 mi), about one-sixth of the circumference of the planet. Crust composition Oxygen 43% Silicon 21% Aluminium 10% Calcium 9% Iron 9% Magnesium 5% Titanium 2% Nickel 0. ...

Complex channels include anastomosed networks, in addition to distribution networks. This type of channel has been observed in association with several impact craters and important lava floods related to important lava flow fields. Compound channels are made of both simple and complex segments. The largest of these channels shows an anastomosed web and modified hills similar to those present on Mars. An anastomosis (plural anastomoses) is a connection between two structures, organs or spaces. ... Amongst the findings from the Opportunity rover is the presence of hematite on Mars in the form of small spheres on the Meridiani Planum. ...

Although the shape of these channels is highly suggestive of fluid erosion, there is no evidence that they were formed by water. In fact, there is no evidence of water anywhere on Venus in the last 600 million years. While the most popular theory for the channels' formation is that they are the result of thermal erosion by lava, there are other hypotheses, including that they were formed by the heated fluids formed and ejected during impacts.

Surface processes

Water does not exist on Venus, and thus the only erosive process to be found (apart from thermal erosion by lava flows) is the interaction produced by the atmosphere with the surface. This interaction is present in the ejecta of impact craters, which has been expelled onto the surface of Venus. The material ejected during a meteorite impact is lifted to the upper atmosphere, where winds transport the material toward the west. As the material is deposited on the surface, it forms parabola-shaped patterns. This type of deposit can be established on top of various geologic features or lava flows. Therefore, these deposits are the youngest structures on the planet. Images from Magellan reveal the existence of more than 60 of these parabola-shaped deposits that are associated with crater impacts. Severe soil erosion in a wheat field near Washington State University, USA. Erosion is the displacement of solids (soil, mud, rock, and so forth) by the agents of wind, water, ice, movement in response to gravity, or living organisms (in the case of bioerosion). ... A meteorite is a small extraterrestrial body that reaches the Earths surface. ... A parabola The parabola (from the Greek: παραβολή) is a conic section generated by the intersection of a cone and a plane tangent to the cone or parallel to some plane tangent to the cone. ...

The ejection material, transported by the wind, is responsible for the process of renovation of the surface at speeds, according to the measurements of the Venera soundings, of approximately one metre per second. Given the density of Venus' lower atmosphere, the winds are more than sufficient to provoke the erosion of the surface and the transportation of fine-grained material. In the regions covered by ejection deposits one may find wind lines, dunes, and yardangs. The wind lines are formed when the wind blows ejection material and volcano ash, depositing it on top of topographic obstacles such as domes. As a consequence, the leeward sides of domes are exposed to the impact of small grains that remove the surface cap. Such processes expose the material beneath, which has a different roughness, and thus different characteristics under radar, compared to formed sediment. A yardang near Meadow, Texas (USDA photo by J.E. Stout). ... Leeward is the side of a boat away from the direction where the wind is coming (i. ...

The dunes are formed by the depositing of particulates that are the size of grains of sand and have wavy shapes. Yardangs are formed when the wind-transported material carves the fragile deposits and produces deep furrows.

The line-shaped patterns of wind associated with impact craters follow a trajectory in the direction of the equator. This tendency suggests the presence of a system of circulation of Hadley cells between the medium latitudes and the equator. Magellan radar data confirm the existence of strong winds that blow toward the east in the upper surface of Venus, and meridional winds on the surface. This article is about impact craters, also known as meteor craters. ... The major driving force of atmospheric circulation in the tropical regions is solar heating. ... Meridional is a geographic term that means along a north-south direction, or relative to a meridian (opposite: zonal, east-west). ...

Meteor impacts on Venus have occurred for the last hundreds of millions of years. The superposition of lava flows can be noted. The oldest lava flows, covered by the newest flows, present distinct intensities on radar reflection. The oldest flows reflect less than the plains that surround the flows. Data from Magellan show that the most recent flows are similar to aa and pāhoehoe. However, the oldest lava flows are darker and look like deposits in arid regions of the Earth that have suffered meteor impacts. Lava is molten rock that a volcano expels during an eruption. ...

Chemical and mechanical erosion of the old lava flows is caused by reactions of the surface with the atmosphere in the presence of carbon dioxide and sulphur dioxide. These two gases are the first and third most abundant gases, respectively; the second most abundant gas is inert nitrogen. The reactions probably include the deterioration of silicates by carbon dioxide to produce carbonates and quartz, as well as the deterioration of silicates by sulphur dioxide to produce anhydrate calcium sulfate and carbon dioxide. Carbon dioxide is an atmospheric gas comprised of one carbon and two oxygen atoms. ... Sulfur dioxide (or Sulphur dioxide) has the chemical formula SO2. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless Atomic mass 14. ... In chemistry, a silicate is a compound consisting of silicon and oxygen (SixOy), one or more metals, and possibly hydrogen. ... Carbonate is an anion with a charge of -2 and an empirical formula of CO32-. For an aqueous solution, carbonate exists in three forms. ... Quartz is the most abundant mineral in the Earths continental crust. ... An Anhydrate (from the Greek word án(h)ydros meaning water loss) is a chemical compound that lacks a whole number of molecules of water. ... Calcium sulfate is a common laboratory and industrial chemical. ...

One of the most interesting characteristics of radar images is the diminishing of reflection at high altitudes, exhibiting values extremely low beyond a radius of 6,054 kilometres (3762 mi). This change is related to the diminishing of emission, and is related to the diminishing of temperature at high altitudes. Temperature is the physical property of a system which underlies the common notions of hot and cold; the material with the higher temperature is said to be hotter. ...

There are various hypotheses for the unusual characteristics of Venus' surface. One idea is that the surface consists of loose ground with spherical hollows that that produce an efficient reflection of radar. Another idea is that the surface is not smooth and is covered by material that has an extremely high dielectric constant. Yet another theory says that the layer one metre above the surface is formed by sheets of a conductive material such as pyrite. Last, a recent model supposes the existence of a small proportion of ferroelectric mineral. The dielectric constant εr (represented as or K in some cases) is defined as the ratio: where εs is the static permittivity of the material in question, and ε0 is the vacuum permittivity. ... The mineral pyrite, or iron pyrite, is iron disulfide, FeS2. ... In physics, the ferroelectric effect is an electrical phenomenon whereby certain ionic crystals may exhibit a spontaneous dipole moment. ...

Ferroelectric minerals exhibit a unique property at high temperatures: the dielectric constant increases abruptly, yet as the temperature increases further, the dielectric constant returns to its normal values. The minerals that could explain this behaviour on the surface of Venus are perovskite and pyrochlores. Perovskite (calcium titanium oxide, CaTiO3) is a relatively rare mineral occurring in orthorhombic (pseudocubic) crystals. ... Pyrochlore (Na,Ca)2Nb2O6(OH,F) is a niobate of calcium, cerium, and other bases, occurring usually in octahedrons of a yellowish or brownish color and resinous luster. ...

Despite these theories, the existence of ferroelectric minerals on Venus has not been confirmed. Only in situ exploration will permit the explanation of such unresolved enigmas.

See also

• Magellan probe
• List of craters on Venus
• List of mountains on Venus

Magellan spacecraft at Kennedy Space Center The Magellan spacecraft carried out a mission from 1989-1994, orbiting Venus from 1990-1994. ... This is a list of named craters on Venus. ... This is a list of mountains on the planet Venus. ...

References

• This article draws heavily on the corresponding article in the Spanish-language Wikipedia, which was accessed in the version of July 9, 2005.
• Grayzeck, Ed (2004). Venus Fact Sheet. NASA. Retrieved July 11, 2005.
• Basilevsky, A. T. and J. W. Head III (2003) "The surface of Venus", Reports on Progress in Physics 66, 1699-1734
• James, Andrew (2003), "Johann Schröter, William Herschel and the Mountains of Venus: Overview", Southern Stars (Journal of the Royal Astronomical Society of New Zealand) 42, 1, March (2003)
• US Geological Survey, "Gazetteer of Planetary Nomenclature (Venus)". Retrieved July 13, 2005
• Vita-Finzi, C., Howarth, R.J., Tapper, S., and Robinson, C. (2004) "Venusian Craters and the Origin of Coronae" Lunar and Planetary Science XXXV
• Stevenson, D. J., (2003). "Planetary magnetic fields", Earth and Planetary Science Letters, 208, 1-11.
• Stofan, E.R., Hamilton, V.E., Janes, D.M., and Smrekar, S.E. (1997) "Coronae on Venus: Morphology and Origin" Venus II Bougher et al., eds., University of Arizona Press, Tucson, 1997

July 9 is the 190th day of the year (191st in leap years) in the Gregorian Calendar, with 175 days remaining. ... 2005 (MMV) is a common year starting on Saturday of the Gregorian calendar. ... NASA Logo Listen to this article · (info) This audio file was created from the revision dated 2005-09-01, and does not reflect subsequent edits to the article. ... July 11 is the 192nd day (193rd in leap years) of the year in the Gregorian Calendar, with 173 days remaining. ... 2005 (MMV) is a common year starting on Saturday of the Gregorian calendar. ... July 13 is the 194th day (195th in leap years) of the year in the Gregorian Calendar, with 171 days remaining. ... 2005 (MMV) is a common year starting on Saturday of the Gregorian calendar. ...

Publications

• The Face of Venus. The Magellan Radar Mapping Mission, by Ladislav E. Roth and Stephen D. Wall. NASA Special Publication, Washington, D.C. June 1995 (SP-520).
• "Estrella del atardecer", El Universo, Enciclopedia de la Astronomía y el Espacio, Editorial Planeta-De Agostini, pgs. 161-167. Part 1 (1997).
• Ciencias de la Tierra. Una Introducción a la Geología Física, by Edward J. Tarbuck and Frederick K. Lutgens. Prentice Hall (1999).
• "Venus," Enciclopedia del Espacio y el Universo, Zeta Multimedia & Dorling Kindersley, Spanish language CD-ROM version (1997).

Related books

• Surface Modification on Venus as Inferred from Magellan Observations on Plains, by R. E. Ardvison, R. Greeley, M. C. Malin, R. S. Saunders, N. R. Izenberg, J. J. Plaut, E. R. Stofan, and M. K. Shepard. Geophisics Research 97, 13.303. (1992)
• The Magellan Imaging Radar Mission to Venus, by W. T. K. Johnson. Proc. IEEE 79, 777. (1991)
• Planetary Landscapes, 3rd Edition, by R. Greeley. Chapman & Hall. (1994)

External links

• The Soviet Exploration of Venus
• Past missions - Mariner 10
• The Voyage of Mariner 10
• Magellan mission to Venus
• Online resources of the Magellan mission to Venus
• Guide for the interpretation of the images taken by Magellan
• Interactive map of Venus
• National Space Science Data Center's Page on Venus (NASA)
• USGS maps of Venus