Tharsis Montes
Encyclopedia
The Tharsis Montes are three large shield volcano
es in the Tharsis
region of the planet Mars
. From north to south, the volcanoes are Ascraeus Mons
, Pavonis Mons
and Arsia Mons
. Mons (plural montes) is the Latin word for mountain. It is a descriptor term used in astrogeology for mountainous features in the Solar System
.
The three Tharsis Montes volcanoes are enormous by terrestrial standards, ranging in diameter from 375 km (Pavonis Mons) to 475 km (Arsia Mons). Ascraeus Mons is the tallest with a summit elevation of over 18 km, or 15 km base-to-peak. For comparison, the largest volcano on Earth, Mauna Loa
in Hawaii
, is about 120 km across and stands 9 km above the ocean floor.
The Tharsis Montes volcanoes lie near the equator, along the crest of a vast volcanic plateau called the Tharsis region or Tharsis buldge. The Tharsis region is thousands of kilometers across and averages nearly 10 km above the mean elevation of the planet. Olympus Mons
, the tallest known mountain
in the Solar System, is located about 1,200 km northwest of the Tharsis Montes, at the edge of the Tharsis region.
The Tharsis Montes were discovered by the Mariner 9
spacecraft in 1971. They were among the few surface features visible as the spacecraft entered orbit during a global dust storm. Appearing as faint spots through the dusty haze, they were informally christened North Spot, Middle Spot, and South Spot. (A fourth spot corresponding to the albedo feature Nix Olympica was also visible and later named Olympus Mons
.) As the dust cleared, it became obvious that the spots were the tops of enormous shield volcano
es with complex central calderas (collapse craters).
The three Tharsis Montes volcanoes are evenly spaced about 700 km apart (from peak to peak) in a line oriented southwest-northeast. This alignment is unlikely to be coincidental. Several volcanic centers northeast of the Tharsis Montes also form part of the line. The line clearly represents a major structural feature of the planet, but its origin is uncertain.
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...
es in the Tharsis
Tharsis
The Tharsis region on Mars is a vast volcanic plateau centered near the equator in Mars’ western hemisphere. The region is home to the largest volcanoes in the Solar System, including the three enormous shield volcanoes Arsia Mons, Pavonis Mons, and Ascraeus Mons, which are collectively known as...
region of the planet Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
. From north to south, the volcanoes are Ascraeus Mons
Ascraeus Mons
Ascraeus Mons is a large shield volcano located in the Tharsis region of the planet Mars. It is the northernmost and tallest of three shield volcanoes collectively known as the Tharsis Montes. The volcano's location corresponds to the classical albedo feature Ascraeus Lacus.Ascraeus Mons was...
, Pavonis Mons
Pavonis Mons
Pavonis Mons is a large shield volcano located in the Tharsis region of the planet Mars. It is the middle member of a chain of three volcanic mountains that straddle the Martian equator between longitudes 235°E and 259°E. The volcano was discovered by the Mariner 9 spacecraft in 1971 and was...
and Arsia Mons
Arsia Mons
Arsia Mons is the southernmost of three volcanos on the Tharsis bulge near the equator of the planet Mars. To its north is Pavonis Mons, and north of that is Ascraeus Mons. The tallest mountain in the solar system, Olympus Mons, is to its northwest...
. Mons (plural montes) is the Latin word for mountain. It is a descriptor term used in astrogeology for mountainous features in the Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
.
The three Tharsis Montes volcanoes are enormous by terrestrial standards, ranging in diameter from 375 km (Pavonis Mons) to 475 km (Arsia Mons). Ascraeus Mons is the tallest with a summit elevation of over 18 km, or 15 km base-to-peak. For comparison, the largest volcano on Earth, Mauna Loa
Mauna Loa
Mauna Loa is one of five volcanoes that form the Island of Hawaii in the U.S. state of Hawaii in the Pacific Ocean, and the largest on Earth in terms of volume and area covered. It is an active shield volcano, with a volume estimated at approximately , although its peak is about lower than that...
in Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
, is about 120 km across and stands 9 km above the ocean floor.
The Tharsis Montes volcanoes lie near the equator, along the crest of a vast volcanic plateau called the Tharsis region or Tharsis buldge. The Tharsis region is thousands of kilometers across and averages nearly 10 km above the mean elevation of the planet. Olympus Mons
Olympus Mons
Olympus Mons is a large volcanic mountain on the planet Mars. At a height of almost , it is one of the tallest mountains in the Solar System, three times as tall as Mount Everest and more than twice the height of Mauna Kea the tallest mountain on Earth. Olympus Mons is the youngest of the large...
, the tallest known mountain
Mountain
Image:Himalaya_annotated.jpg|thumb|right|The Himalayan mountain range with Mount Everestrect 58 14 160 49 Chomo Lonzorect 200 28 335 52 Makalurect 378 24 566 45 Mount Everestrect 188 581 920 656 Tibetan Plateaurect 250 406 340 427 Rong River...
in the Solar System, is located about 1,200 km northwest of the Tharsis Montes, at the edge of the Tharsis region.
The Tharsis Montes were discovered by the Mariner 9
Mariner 9
Mariner 9 was a NASA space orbiter that helped in the exploration of Mars and was part of the Mariner program. Mariner 9 was launched toward Mars on May 30, 1971 from Cape Canaveral Air Force Station and reached the planet on November 13 of the same year, becoming the first spacecraft to orbit...
spacecraft in 1971. They were among the few surface features visible as the spacecraft entered orbit during a global dust storm. Appearing as faint spots through the dusty haze, they were informally christened North Spot, Middle Spot, and South Spot. (A fourth spot corresponding to the albedo feature Nix Olympica was also visible and later named Olympus Mons
Olympus Mons
Olympus Mons is a large volcanic mountain on the planet Mars. At a height of almost , it is one of the tallest mountains in the Solar System, three times as tall as Mount Everest and more than twice the height of Mauna Kea the tallest mountain on Earth. Olympus Mons is the youngest of the large...
.) As the dust cleared, it became obvious that the spots were the tops of enormous shield volcano
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...
es with complex central calderas (collapse craters).
The three Tharsis Montes volcanoes are evenly spaced about 700 km apart (from peak to peak) in a line oriented southwest-northeast. This alignment is unlikely to be coincidental. Several volcanic centers northeast of the Tharsis Montes also form part of the line. The line clearly represents a major structural feature of the planet, but its origin is uncertain.