Mars
Can you guess why Mars, the fourth planet from the Sun, has been called the red planet? Iron oxide in the weathered rocks on its surface gives it a reddish-yellow color. Other features of Mars visible from Earth are its polar ice caps and changes in the coloring of the planet's surface. The ice caps are made mostly of frozen carbon dioxide and frozen water.
Most of the information scientists have about Mars came from Mariner 9, the Viking probes, Mars Global Surveryor, and Mars Pathfinder. Mariner 9 orbited Mars in 1971 and 1972. It revealed long channels on the planet that might have been carved by flowing water. Mariner 9 also discovered the largest volcano in the solar system, Olympus Mons. Olympus Mons is probably extinct. Large rift valleys that formed in the Martian crust also were discovered. One such valley is Valles Marineris. Mars is tilted on its axis by 25 degrees.
Mars Atmosphere
The Viking and Global and Global Surveyor probes analyzed gases in the Martian atmosphere and determined atmosperic pressure and temperature. They found that Mar's atmosphere is much thinner than Earth's. It is composed mostly of carbon dioxide, with some nitrogen and argon. Surface temperatures range from -125 C to 35 C. The temperature difference between day and night results in strong winds on the planet, which can cause global dust storms during certain seasons. This information will help in planning possible human exploration of Mars in the future.
Martian Moons
Mars has two small, irregularly shaped moons that are heavily cratered. Phobos is about 25 kilometers in length. Deimos is about 13 kilometers in length. Deimos orbits Mars once every 31 hours, while Phobos speeds around Mars once every 7 hours.
Phobos has grooves on its surface that seem to radiate out in all directions from the giant Stickney Crater. Some of the grooves are 700 meters across and 90 meters deep. Phobo's orbit is spiraling slowly inward toward Mars. It is expected to crash into the Martian surface in about 50 million years.
Deimos is the outer of Mars's two moons. it is among the smallest known moons in the solar system. Its surface is smoother in appearance than that of Phobos because some of its craters have partially filled with soil and rock.
Most of the information scientists have about Mars came from Mariner 9, the Viking probes, Mars Global Surveryor, and Mars Pathfinder. Mariner 9 orbited Mars in 1971 and 1972. It revealed long channels on the planet that might have been carved by flowing water. Mariner 9 also discovered the largest volcano in the solar system, Olympus Mons. Olympus Mons is probably extinct. Large rift valleys that formed in the Martian crust also were discovered. One such valley is Valles Marineris. Mars is tilted on its axis by 25 degrees.
Mars Atmosphere
The Viking and Global and Global Surveyor probes analyzed gases in the Martian atmosphere and determined atmosperic pressure and temperature. They found that Mar's atmosphere is much thinner than Earth's. It is composed mostly of carbon dioxide, with some nitrogen and argon. Surface temperatures range from -125 C to 35 C. The temperature difference between day and night results in strong winds on the planet, which can cause global dust storms during certain seasons. This information will help in planning possible human exploration of Mars in the future.
Martian Moons
Mars has two small, irregularly shaped moons that are heavily cratered. Phobos is about 25 kilometers in length. Deimos is about 13 kilometers in length. Deimos orbits Mars once every 31 hours, while Phobos speeds around Mars once every 7 hours.
Phobos has grooves on its surface that seem to radiate out in all directions from the giant Stickney Crater. Some of the grooves are 700 meters across and 90 meters deep. Phobo's orbit is spiraling slowly inward toward Mars. It is expected to crash into the Martian surface in about 50 million years.
Deimos is the outer of Mars's two moons. it is among the smallest known moons in the solar system. Its surface is smoother in appearance than that of Phobos because some of its craters have partially filled with soil and rock.