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Mars
[History | Information
| Moons | Data]
| For information on the Mars Missions click the link below. Click here
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Mars is names after the Roman god of war. Mars is about half the size of Earth, with
about one tenth of the mass. Mars is very similar to earth is a lot of ways. It has a
similar rotational period as Earth. Its yearly orbit is twice that of Earth's. It also has
many of the same land features and shows evidence of once having water.
However, Mars is much colder than Earth, and its small size has affected its ability to
retain an atmosphere.
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The atmosphere on Mars is very similar in composition to that of Venus, but much
thinner. Mars's weak gravitational field accounts for this because it can't hold in the
smaller molecules and light gasses. The CO2 atmosphere therefore does not
contribute greatly to any greenhouse effect. Like Earth, Mars has polar ice caps which are
composed of water ice and carbon dioxide ice (dry ice).
The dried-out river channels on Mars give evidence of once having
water on its surface (as mentioned above). When the planet was cooling after its
formation, water vapor was probably out-gassed. The water then condensed into clouds and
rained down onto the surface to form lakes and rivers. Much like the Earth. Water could
also have been released from through the ground (mudslides and geysers). With a lack of an
ozone layer, however, the water molecules could be broken-up into their elemental forms,
Hydrogen and Oxygen. These gasses are light enough to escape Mars's gravitational field.
Mars has not water in its liquid state, only frozen in its polar ice caps below the
surface.
Mars has a very thick outer curst, this determines many of the surface features on the
planet. The largest volcano in the solar system is on Mars, Olympus Mons, and it twice as
large as the largest volcano on Earth. Its base is the size of Missouri. Also, the largest
valley in the solar system is located on Mars. In a region called Tharsis an large bulge
about 10km above the surface has formed. Near the bulge is the Valles Marineris, named
after the Mariner Space Probe that discovered it. This valley is long enough to reach from
New York to Los Angeles and in some places 4 miles deep.
The surface of Mars is red because it has rusted over the years. It has a great deal of
iron that has oxidized on the surface.
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Mars has two moons:
Name of Satellite
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Average diameter in km
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| Phobos |
24 |
| Deimos |
14 |
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Distance from Sun:
Mean— 141,000,000 mi.
Shortest— 128,400,000 mi.
Greatest— 154,800,000 mi.
Closest approach to Earth— 34,600,000 mi.
Length of year (earth-days)— 686.98
Average orbital speed— 14.99 mi. per sec.
Diameter at equator— 4,223
Rotation period— 24 hrs. 37 min.
Tilt of axis "(degrees)— 23.98
Temperature— -225 to 63 *F
Atmosphere:
Pressure— 0.1 lbs. per sq. in
Gasses— Carbon dioxide, nitrogen, argon, oxygen, carbon monoxide, neon, krypton,
xenon, water vapor.
Mass (Earth=1)— 0.107
Density (g/cubic cm)— 3.94
Gravity (Earth=1)— 0.38
Number of known satellites— 2 |
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[Mercury | Venus | Earth | Mars | Jupiter]
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