Mars, the red planet, namesake of the Roman God of War. About 5/8 of the surface of Mars is a desert of reddish rock, sand, and soil. The rest is covered by irregular patches that appear generally green, in hues that change throughout the year (World Almanac 298). These green patches were thought to be vegetation but the results from Mariner 4s exploration disproved this. Like Earth, Mars has seasons; its polar caps grow during the winter and shrink during the summer (298). Mars has Valles Marinaris, a valley that is longer than the United States, and Olympus Mons the largest known volcano in the solar system, is wider than the state of Arizona and almost three times higher than Mauna Loa, in Hawaii (Audubon 651).
Planet Profile
(Data compiled from Mars, and MARS
and Satellites - Data.)
Average distance from the Sun
...1.525
AU
Mass
6.42 x 10^23
kg
Diameter
...6787
km
Average density
...2940
kg/m^3
Length of day
..24
hrs 37 mins
Length of year
.687
(Earth) days
Inclination (tilt) of axis
..
..25
degrees
Inclination to ecliptic
1.85
degrees
Maximum surface temperature
310
K
Minimum surface temperature
150
K
Highest point on surface
..Olympus
Mons
Atmospheric components
Carbon
dioxide, nitrogen, & argon
Number of observed satellites (Moons)
.2 (Deimos and Phobos)
Deimos and Phobos are Mars moons; in mythology, they were his sons by Venus. In 1610 Johannes Kepler knew of their existence and asked Galileo for a telescope so he could prove it (Barbree, Caidin, and Wright 54). Unfortunately, Galileo denied his request, claiming that he had none to spare (55). They were not discovered until 1877, by the astronomer Asaph Hall, who also named them (69). Unlike our Moon they are probably captured asteroids that resemble lumpy potatoes. The nearest to Mars and larger, Phobos, rises in the west and sets in the east two or three times each Martian day. Deimos the outer and smaller moon rises in the east and moves westward very slowly across the sky, remaining above the horizon for several Mars days (Audubon 652-653).