Mars is a favorite among scientists, astronomers, and the public. Simply mentioning the planet will conjure images of canals, Martians, and rovers roaming the rusty red desert. Of all the planets, Mars is the one with endless ponderings.
Mars is the fourth planet from the Sun with an average distance of 142 million miles. It can get as close as 128 million miles or as far as 154 million miles from the Sun.
Mars is the third smallest planet with a diameter of 4220 miles and has two moons.
A day on Mars is almost like Earth’s being 24 hours and 37 minutes, but its year is nearly twice as long at 687 days.
Mars can come as close to Earth as 34.6 million miles or as far as 248 million miles, therefore its size can range from 3.5 to 25.2 arc-seconds across.
Mars has the greatest fluctuation in brilliance of any planet as seen from Earth. It can shine as bright as magnitude -2.9 when closest to Earth during opposition or as dim as magnitude +1.8 when farthest away on the other side of the Sun.
Because Mars orbits farther from the Sun than Earth It can never appear in a crescent or half phase. At minimum phase Mars is distinctly gibbous at approximately 85% lit.
Giovanni Schiaparelli began the canal controversy by observing a network of fine lines on Mars. Percival Lowell advanced the theory by reasoning that they were true canals built by a dying civilization irrigating the desert, but they were nothing more than an illusion.
A seasonal wave of darkening was also believed to be the greening of the deserts from melting polar ice caps. This darkening is nothing more than seasonal winds moving the dust around.
The height of the Martian Mania came on the night of October 30, 1938 with the radio broadcast of “War of the Worlds” by Orson Welles. Many believed Earth was being attacked by Martians.
The theory of life on Mars took a fatal blow in the 1940s and 1950s when Mars was found to be too cold, too dry and have only a thin atmosphere of mainly carbon dioxide.
The atmosphere is composed of 95% carbon dioxide with the rest comprised mainly of nitrogen. The atmosphere pressure is only 1% of Earth’s with the greatest pressure in the Hellas Basin and the lowest pressure on top of Olympus Mons.
The average temperature of Mars is -64° F, but can be as warm as 70° F near the equator or as frigid as -150° F at the poles.
Winds can approach 150 miles per hour creating global dust storms, but is less forceful than on Earth due to the thin atmosphere.
Dust devils tower several miles into the sky appearing like red tornadoes and packing winds up to 150 miles per hour.
The red color of Mars is due to iron oxide. Mars is truly a rusty planet.
Olympus Mons (Mount Olympus) is the tallest volcano on Mars and in the Solar System towering 15 miles high.
Valles Marineris (Mariner Valley) is the grandest canyon on Mars and in the Solar System. It is up to 20,000 feet deep, 120 miles wide, and 3000 miles long.
Hellas is the deepest basin on Mars and in the Solar System. It is around 1100 miles in diameter and up to 5 miles deep.
All of the water from the ice caps, atmosphere, and beneath the ground could fill Lake Michigan.
Mars has evidence of running water on its surface during the past and perhaps the present. There are vast outflow channels and erosion that have the characteristics of large volumes of running water.
The two Martian moons, Phobos and Deimos, may be captured asteroids. They were discovered by Asaph Hall during August 1877.
Phobos is 17x13x12 miles across and Deimos is 9x7.4x7 miles across. Phobos orbits only 3700 miles above the surface of Mars and Deimos only 12,500 miles.
Phobos rises in the west and sets in the east at least twice per day and crosses the sky in 4 ½ hours while Deimos rises in the east and sets in the west, but takes 60 hours to do so.
Phobos eclipses the Sun 1300 times per year and Deimos 130 times, but neither would produce a total eclipse. Deimos’ shadow would barely be noticed.
Phobos is so close to Mars that there is a real danger of it crashing into Mars in about 100 million years, therefore it has already lived 98% of its life.
Mariner 9 became the first spacecraft to orbit another planet when it arrived at Mars on November 14, 1971.
Viking 1 became the first spacecraft to transmit a color photo of the surface of another planet when it landed on Mars on July 20, 1976.
Sojourner became the first rover on another planet when Pathfinder landed on Mars on July 4, 1997.
The Opportunity Rover became the first spacecraft to directly prove during 2004 that water once covered portions of Mars.
Thirty-six spacecraft as of 2005 have visited Mars, but only fourteen have been successful, for a dismal success rate of 39%. Japan’s Nozomi orbiter and Great Britain’s Beagle 2 lander were the latest failures. Europe’s Mars Express orbiter and the U.S. rovers, Spirit and Opportunity, are the latest successes.
No other planet is undergoing such intense exploration and no other planet stirs the imagination more than Mars. The best ponderings of Mars have yet to come with the advent of the first sample return mission and the first manned landing.