Maat Mons is a massive shield volcano on the

planet A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...

Venus Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never f ...

and the planet's second-highest

mountain A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited summit area, and is usually highe ...

and highest

volcano A volcano is a rupture in the Crust (geology), crust of a Planet#Planetary-mass objects, planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and volcanic gas, gases to escape from a magma chamber below the surface. On Ear ...

. It rises above the mean planetary radius at , and nearly 5 km above the surrounding

plain In geography, a plain is a flat expanse of land that generally does not change much in elevation, and is primarily treeless. Plains occur as lowlands along valleys or at the base of mountains, as coastal plains, and as plateaus or uplands ...

s. It is named after the Egyptian goddess of truth and justice,

Ma'at Maat or Maʽat ( Egyptian: mꜣꜥt /ˈmuʀʕat/, Coptic: ⲙⲉⲓ) refers to the ancient Egyptian concepts of truth, balance, order, harmony, law, morality, and justice. Ma'at was also the goddess who personified these concepts, and regul ...

Structure

Maat Mons has a large summit

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...

, 28×31 km in size. Within the large caldera, there are at least five smaller collapse craters, up to 10 km in diameter. A chain of small craters 3–5 km in diameter extends some 40 km along the southeast flank of the volcano, but rather than indicating a large

fissure A fissure is a long, narrow crack opening along the surface of Earth. The term is derived from the Latin word , which means 'cleft' or 'crack'. Fissures emerge in Earth's crust, on ice sheets and glaciers, and on volcanoes. Ground fissure ...

eruption, they seem to also be formed by collapse: full resolution imagery from the ''

Magellan Ferdinand Magellan ( or ; pt, Fernão de Magalhães, ; es, link=no, Fernando de Magallanes, ; 4 February 1480 – 27 April 1521) was a Portuguese explorer. He is best known for having planned and led the 1519 Spanish expedition to the East ...

'' 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.

Activity

Radar Radar is a detection system that uses radio waves to determine the distance ('' ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, we ...

sounding by ''Magellan'' probe revealed evidence for comparatively recent volcanic activity at Maat Mons, in the form of

ash flow A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of b ...

s near the summit and on the northern flank. Intriguingly for planetary geologists, atmospheric studies carried out by the

Pioneer Venus The Pioneer Venus project was part of the Pioneer program consisting of two spacecraft, the Pioneer Venus Orbiter and the Pioneer Venus Multiprobe, launched to Venus in 1978. The program was managed by NASA's Ames Research Center. The Pio ...

probes in the early 1980s revealed a considerable variation in the concentrations of sulfur dioxide (SO₂) and

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Ea ...

(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. More recent studies have suggested that the volcano structure, distribution of lava flows, pit craters, summit morphology, and other small-scale features are indicative of recent volcanic activity on 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.

References

External links

3D Perspective View of Maat Mons
{{Venus Volcanoes of Venus Mountains on Venus Polygenetic shield volcanoes

Structure

Activity

See also

References

External links