Olympus Mons
The largest of the volcanoes in the Tharsis Montes region, as well as all known volcanoes in the solar system, is Olympus Mons. Olympus Mons is a shield volcano 624 km (374 mi) in diameter (approximately the same size as the state of Arizona), 25 km (16 mi) high, and is rimmed by a 6 km (4 mi) high scarp. A caldera 80 km (50 mi) wide is located at the summit of Olympus Mons. To compare, the largest volcano on Earth is Mauna Loa. Mauna Loa is a shield volcano 10 km (6.3 mi) high and 120 km (75 mi) across. The volume of Olympus Mons is about 100 times larger than that of Mauna Loa. In fact, the entire chain of Hawaiian islands (from Kauai to Hawaii) would fit inside Olympus Mons!
The largest of the volcanoes in the Tharsis Montes region, as well as all known volcanoes in the solar system, is Olympus Mons. Olympus Mons is a shield volcano 624 km (374 mi) in diameter (approximately the same size as the state of Arizona), 25 km (16 mi) high, and is rimmed by a 6 km (4 mi) high scarp. A caldera 80 km (50 mi) wide is located at the summit of Olympus Mons. To compare, the largest volcano on Earth is Mauna Loa. Mauna Loa is a shield volcano 10 km (6.3 mi) high and 120 km (75 mi) across. The volume of Olympus Mons is about 100 times larger than that of Mauna Loa. In fact, the entire chain of Hawaiian islands (from Kauai to Hawaii) would fit inside Olympus Mons!
Here are some more pictures to make a point of how big Olympus Mons is. ;)
Deimos
Deimos is the smaller of Mars' two moons. Being only 15 by 12 by 11 km in size, Deimos whirls around Mars every 30 hours. Like Phobos, Deimos is a small lumpy, heavily cratered object. Its craters are generally smaller than 2.5 km in diameter, however, and it lacks the grooves and ridges seen on Phobos. Typically when a meteorite hits a surface, surface material is thrown up and out of the resulting crater. The material usually falls back to the surface surrounding the crater. However, these ejecta deposits are not seen on Deimos, perhaps because the moon's gravity is so low that the ejecta escaped to space. Material does appear to have moved down slopes. Deimos also has a thick regolith, perhaps as deep as 100 m, formed as meteorites pulverized the surface. Deimos is a dark body that appears to be composed of C-type surface materials, similar to that of asteroids found in the outer asteroid belt.
Deimos is the smaller of Mars' two moons. Being only 15 by 12 by 11 km in size, Deimos whirls around Mars every 30 hours. Like Phobos, Deimos is a small lumpy, heavily cratered object. Its craters are generally smaller than 2.5 km in diameter, however, and it lacks the grooves and ridges seen on Phobos. Typically when a meteorite hits a surface, surface material is thrown up and out of the resulting crater. The material usually falls back to the surface surrounding the crater. However, these ejecta deposits are not seen on Deimos, perhaps because the moon's gravity is so low that the ejecta escaped to space. Material does appear to have moved down slopes. Deimos also has a thick regolith, perhaps as deep as 100 m, formed as meteorites pulverized the surface. Deimos is a dark body that appears to be composed of C-type surface materials, similar to that of asteroids found in the outer asteroid belt.
Phobos
Phobos, gouged and nearly shattered by a giant impact crater and beaten by thousands of meteorite impacts, is on a collision course with Mars. Phobos is the larger of Mars' two moons and is 27 by 22 by 18 km in diameter. It orbits Mars three times a day, and is so close to the planet's surface that in some locations on Mars it cannot always be seen. Phobos is nearing Mars at a rate of 1.8 m every hundred years; at that rate, it will either crash into Mars in 50 million years or break up into a ring. Its most prominent feature is the 6-mile crater Stickney, its impact causing streak patterns across the moon's surface. Stickney was seen by Mars Global Surveyor to be filled with fine dust, with evidence of boulders sliding down its sloped surface. Phobos and Deimos appear to be composed of C-type rock, similar to blackish carbonaceous chondrite asteroids. Observations by Mars Global Surveyor indicate that the surface of this small body has been pounded into powder by eons of meteoroid impacts, some of which started landslides that left dark trails marking the steep slopes of giant craters. Measurements of the day and night sides of Phobos show such extreme temperature variations that the sunlit side of the moon rivals a pleasant winter day in Chicago, while only a few kilometers away, on the dark side of the moon, the climate is more harsh than a night in Antarctica. High temperatures for Phobos were measured at 25 degrees Fahrenheit (-4 degrees Celsius) and lows at -170 degrees Fahrenheit (-112 degrees Celsius). This intense heat loss is likely a result of the fine dust on Phobos' surface, which is unable to retain heat. Phobos has no atmosphere. It may be a captured asteroid, but some scientists show evidence that contradicts this theory.
Phobos, gouged and nearly shattered by a giant impact crater and beaten by thousands of meteorite impacts, is on a collision course with Mars. Phobos is the larger of Mars' two moons and is 27 by 22 by 18 km in diameter. It orbits Mars three times a day, and is so close to the planet's surface that in some locations on Mars it cannot always be seen. Phobos is nearing Mars at a rate of 1.8 m every hundred years; at that rate, it will either crash into Mars in 50 million years or break up into a ring. Its most prominent feature is the 6-mile crater Stickney, its impact causing streak patterns across the moon's surface. Stickney was seen by Mars Global Surveyor to be filled with fine dust, with evidence of boulders sliding down its sloped surface. Phobos and Deimos appear to be composed of C-type rock, similar to blackish carbonaceous chondrite asteroids. Observations by Mars Global Surveyor indicate that the surface of this small body has been pounded into powder by eons of meteoroid impacts, some of which started landslides that left dark trails marking the steep slopes of giant craters. Measurements of the day and night sides of Phobos show such extreme temperature variations that the sunlit side of the moon rivals a pleasant winter day in Chicago, while only a few kilometers away, on the dark side of the moon, the climate is more harsh than a night in Antarctica. High temperatures for Phobos were measured at 25 degrees Fahrenheit (-4 degrees Celsius) and lows at -170 degrees Fahrenheit (-112 degrees Celsius). This intense heat loss is likely a result of the fine dust on Phobos' surface, which is unable to retain heat. Phobos has no atmosphere. It may be a captured asteroid, but some scientists show evidence that contradicts this theory.
Asteroid Belt
Scattered in orbits around the sun are bits and pieces of rock left over from the dawn of the solar system. Most of these objects, called planetoids or asteroids — meaning "star-like" — orbit between Mars and Jupiter in a grouping known as the Main Asteroid Belt. The Main Asteroid Belt lies more than two-and-a-half times as far as Earth does from the sun. It contains billions — maybe even trillions — of asteroids. Most of these are relatively small, from the size of boulders to a few thousand feet in diameter. But some are significantly larger.
Scattered in orbits around the sun are bits and pieces of rock left over from the dawn of the solar system. Most of these objects, called planetoids or asteroids — meaning "star-like" — orbit between Mars and Jupiter in a grouping known as the Main Asteroid Belt. The Main Asteroid Belt lies more than two-and-a-half times as far as Earth does from the sun. It contains billions — maybe even trillions — of asteroids. Most of these are relatively small, from the size of boulders to a few thousand feet in diameter. But some are significantly larger.
Valles Marineris
Valles Marineris, or Mariner Valley, is a vast canyon system that runs along the Martian equator just east of the Tharsis region. Valles Marineris is 4000 km (2500 mi) long and reaches depths of up to 7 km (4 mi)! For comparison, the Grand Canyon in Arizona is about 800 km (500 mi) long and 1.6 km (1 mi) deep. In fact, the extent of Valles Marineris is as long as the United States and it spans about 20 percent (1/5) of the entire distance around Mars! The canyon extends from the Noctis Labyrinthus region in the west to the chaotic terrain in the east. Most researchers agree that Valles Marineris is a large tectonic "crack" in the Martian crust, forming as the planet cooled, affected by the rising crust in the Tharsis region to the west, and subsequently widened by erosional forces. However, near the eastern flanks of the rift there appear to be some channels that may have been formed by water.
Valles Marineris, or Mariner Valley, is a vast canyon system that runs along the Martian equator just east of the Tharsis region. Valles Marineris is 4000 km (2500 mi) long and reaches depths of up to 7 km (4 mi)! For comparison, the Grand Canyon in Arizona is about 800 km (500 mi) long and 1.6 km (1 mi) deep. In fact, the extent of Valles Marineris is as long as the United States and it spans about 20 percent (1/5) of the entire distance around Mars! The canyon extends from the Noctis Labyrinthus region in the west to the chaotic terrain in the east. Most researchers agree that Valles Marineris is a large tectonic "crack" in the Martian crust, forming as the planet cooled, affected by the rising crust in the Tharsis region to the west, and subsequently widened by erosional forces. However, near the eastern flanks of the rift there appear to be some channels that may have been formed by water.