The surface of Mars has been easily observable from earth for several centuries, but it is only recently that our observations
have been of sufficient detail to make detailed analysis possible. The surface features of Mars are various, some familiar,
some unique to the planet.
Olympus Mons a huge shield volcano in the northern hemisphere in a region called Tharsis. .
We have seen that Mars also has polar ice caps, and a face? The Face on Mars is just an illusion formed by light and shadow,
isn't it?
Most impressive is Valles Marineris, a 4000 km wide crack around the equator of Mars. Valles Marineris was discovered by the
Mariner 9 probe, hence, its name. Here is Valles Marineris in 3D!
Mars has a radius of 3396 km, which is
approximately one half that of Earth. This gives
the planet about the same surface area as the land
area of Earth.
Mars rotates in 24 hours 37 minutes at the sidereal rate,
referenced to the stars. Its synodic day, from noon to
noon, is 24 hours 39 minutes. This is very near Earth’s
rate of rotation. The day on the surface of Mars would
seem very familiar to an earthling.
Mars orbits the Sun at an average distance of 5.2
A.U. and takes 1.87 years to complete one
revolution. Because of its axial tilt, it has seasons,
just as Earth. But each of its seasons is about
twice as long.
The atmosphere of Mars consists of 96%
carbon dioxide. The remaining 3% is mostly nitrogen.
The pressure at the surface varies from from 4.0 to 8.7
mb (depending on season). We occasionally see clouds
in Mars' thin atmosphere.
Since it lacks an appreciable iron core, Mars has
no self-generated magnetic field. This results in
radiation levels at the surface that would be
harmful for human beings.
Mars does have the ocassional thin cloud
layer. However, the clouds may consist of
carbon dioxide ice crystals rather than
water droplets.
Foolish Earthling! Mars has no rings!
