Mars' Statistics

Mars

Equatorial diameter
4,200 miles(6,790 kilometers)

Mass
0.11(Earth=1)

Mean relative density
3.95(Water=1)

Surface gravity
0.38(Earth=1)

Escape velocity
3 miles(5 kilometers) per second

Distance from Sun
farthest:154,900,000 miles(249,200,000 kilometers) nearest:128,500,000 miles(206,800,000) mean:141,700,000 miles(228,000,000 kilometers)

Closest approach to earth
approx. 48,700,000 miles(78,390,000 kilometers)

Orbital period
687 earth-days

Rotational period
24 hours and 37 minutes

Satellites
2(Phobos & Deimos)

Mars

Of all the planets, Mars has fascinated human beings the most. Its fiery orange-red hue makes it a distinctive site in the night sky and has earned it the name of the Red Planet. The Romans named it after Mars, their god of war.

Although much smaller than the earth, Mars shows many similarities to our own planet. It has seasons, and its day is a little over 24 hours long. There is also an atmosphere, although a very slight one, and icecaps at the poles.

Mars has two satellites, discovered by Asaph Hall in 1877, and named him by him Phobos and Deimos (Fear and Terror). The origin of these satellites is unknown, although their composition and small size Phobos is about 14 miles(23 kilometers) across and Deimos 6 miles (10 kilometers) have led to suggestions that originally they might have been asteroids that were "captured" by Mars.

In the late 1800's, astronomers began observing Mars closely with ever more powerful telescopes. In 1877, the Italian astronomer Giovanni Schiaparelli reported seeing "canals" on the surface of the planet. Astronomers also noted the so-called "wave of darkening" that sweeps over the planet in spring. These observations suggested to many people that Mars must be inhabited by intelligent creatures. One of the most avid supporters of this theory in the 1890's was the American astronomer Percival Lowell, who built an observatory at Flagstaff, Arizona, specifically to observe Mars and its surface features.

As time went on and more powerful instruments were trained on Mars, it became less and less likely that the planet could support life of any kind. When spacecraft began observing the planet close-up from 1965 onward, the prospects of life virtually vanished. In 1976, Viking spacecraft soft landed on Mars and sent back television pictures of a barren waterless landscape. They also searched for signs of life by sampling the soil, but they searched in vain. They could find no traces of any kind of organic matter.