Maat Mons
Encyclopedia
Maat Mons is a massive shield volcano
and the highest volcano on the planet
Venus
. It rises 8 kilometres (5 mi) above the mean planetary radius at 0.5°N 194.6°E. It is named after the Egyptian goddess of truth and justice, Ma'at.
, 28×31 km in size. Within the large caldera there are at least five smaller collapse crater
s, up to 10 km in diameter.
A chain of small craters 3–5 km in diameter extends some 40 km along the south west flank of the volcano, but rather than indicating a large fissure
eruption, they seem to also be formed by collapse: full resolution imagery from the Magellan probe
reveals no evidence of lava flows from these craters.
At least two large scale structural collapse events seem to have occurred in the past on Maat Mons.
sounding by the Magellan probe revealed evidence for comparatively recent volcanic activity at Maat Mons, in the form of ash
flows near the summit and on the northern flank.
Intriguingly for planetary geologists
, atmospheric studies carried out by the Pioneer Venus probes in the early 1980s revealed a considerable variation in the concentrations of sulfur dioxide
(SO2) and methane
(CH4) in Venus' middle and upper atmosphere. One possible explanation for this was the injection of volcanic gases into the atmosphere by plinian eruptions at Maat Mons.
Although many lines of evidence suggest that Venus is likely to be volcanically active, present-day eruptions at Maat Mons have not been confirmed.
Shield volcano
A shield volcano is a type of volcano usually built almost entirely of fluid lava flows. They are named for their large size and low profile, resembling a warrior's shield. This is caused by the highly fluid lava they erupt, which travels farther than lava erupted from more explosive volcanoes...
and the highest volcano on the planet
Planet
A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...
Venus
Venus
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows...
. It rises 8 kilometres (5 mi) above the mean planetary radius at 0.5°N 194.6°E. It is named after the Egyptian goddess of truth and justice, Ma'at.
Structure
Maat Mons has a large summit calderaCaldera
A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, such as the one at Yellowstone National Park in the US. They are sometimes confused with volcanic craters...
, 28×31 km in size. Within the large caldera there are at least five smaller collapse crater
Volcanic crater
A volcanic crater is a circular depression in the ground caused by volcanic activity. It is typically a basin, circular in form within which occurs a vent from which magma erupts as gases, lava, and ejecta. A crater can be of large dimensions, and sometimes of great depth...
s, up to 10 km in diameter.
A chain of small craters 3–5 km in diameter extends some 40 km along the south west flank of the volcano, but rather than indicating a large fissure
Fissure
In anatomy, a fissure is a groove, natural division, deep furrow, elongated cleft, or tear in various parts of the body.-Brain:...
eruption, they seem to also be formed by collapse: full resolution imagery from the Magellan probe
Magellan probe
The Magellan spacecraft, also referred to as the Venus Radar Mapper, was a 1,035-kilogram robotic space probe launched by NASA on May 4, 1989, to map the surface of Venus using Synthetic Aperture Radar and measure the planetary gravity...
reveals no evidence of lava flows from these craters.
At least two large scale structural collapse events seem to have occurred in the past on Maat Mons.
Activity
RadarRadar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
sounding by the Magellan probe revealed evidence for comparatively recent volcanic activity at Maat Mons, in the form of ash
Volcanic ash
Volcanic ash consists of small tephra, which are bits of pulverized rock and glass created by volcanic eruptions, less than in diameter. There are three mechanisms of volcanic ash formation: gas release under decompression causing magmatic eruptions; thermal contraction from chilling on contact...
flows near the summit and on the northern flank.
Intriguingly for planetary geologists
Planetary geology
Planetary geology, alternatively known as astrogeology or exogeology, is a planetary science discipline concerned with the geology of the celestial bodies such as the planets and their moons, asteroids, comets, and meteorites...
, atmospheric studies carried out by the Pioneer Venus probes in the early 1980s revealed a considerable variation in the concentrations of sulfur dioxide
Sulfur dioxide
Sulfur dioxide is the chemical compound with the formula . It is released by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide unless the sulfur compounds are removed before burning the fuel...
(SO2) and methane
Methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...
(CH4) in Venus' middle and upper atmosphere. One possible explanation for this was the injection of volcanic gases into the atmosphere by plinian eruptions at Maat Mons.
Although many lines of evidence suggest that Venus is likely to be volcanically active, present-day eruptions at Maat Mons have not been confirmed.