The planet Mars is a reddish planet fourth in the order of increasing distance from the sun and it lies next to the earth. It was named after the Roman god of war, because of the ruddy, reddish appearance it gets from the iron oxide on its surface. When Mars is nearest to the earth, it is three times as brilliant as the brightest star in our heavens, Sirius. It averages 141.5 million miles from the sun and it receives one-half the amount of light and solar heat compared to the earth; consequently Mars is colder.
Like the earth's seasonal variation of its north and south polar caps, Mars has brilliant white ice caps that grow at the end of the Martian winter and diminish near summer's end. Approximately two-thirds of Mars is a reddish brown desert and is observed as the bright areas. The dark areas, once thought to have been seas, appear blue-gray in Martian autumn and winter.
The axis of Mars passes between the two stars Cassiopeiae and Alpha Cygni. As a result of this observation, astronomers have been able to assign the inclination of the axis of Mars quite accurately through the measurements of the polar caps as they turn from night to night and from year in to year out.
One of the earliest observations of Mars was recorded in 356 B.C. by Aristotle. Galileo first discovered that Mars had phases with his telescope in 1610. Another observer, Cassini discovered the polar caps of Mars in 1666; however, it was Huygens that made the observation that this planet rotated on its axis in a period slightly longer than our Earth. A Martian year is 687 days and each day on Mars is equal to twenty-four hours and thirty-seven minutes.
The two moons, or satellites, of Mars were discovered by an American astronomer, Asaph Hall, in 1877. Hall named the moons after two characters in Greek mythology, Phobos and Deimos, who were attendants of Ares, the Greek god of war (the Roman Mars). Phobos is the inner satellite and has a diameter of about ten miles. Deimos is the smaller satellite of the two and, like Phobos, moves nearly in the plane of the Martian equator.
A variety of evidence analyzed by the first space probe Viking I, in 1976, pointed to an atmosphere consisting of 1 percent the density of our own and consisting of 0.3 percent oxygen. Martian atmosphere does not possess sufficient gravity to retain water vapor and this may contribute to an atmosphere almost entirely of nitrogen, argon, and carbon dioxide.
A second space probe, Viking 2, was sent to conduct atmospheric and soil analysis. Its findings indicated the surface on Mars is exposed to lethal doses of ultraviolet radiation and that the canals on Mars really do not exist. It was once thought that the concept of a network of canals had been built by a race superior to ours.
As a result of these observations it is improbable that Mars is inhabitable with its frigid temperatures, thin atmosphere and little or no water.