Mars, named after the Roman god of war, is the 4th planet from the sun and has been known since prehistoric times. When its at its nearest to Earth – 35 million miles away – Mars can be seen in great detail even with small telescopes. Mars moves around the Sun at a mean distance of 140 million miles, or about 1.5 times the distance of Earth from the Sun and orbits the Sun once in 687 Earth days, which means that its year is nearly twice as long as Earth’s.
Mars is much smaller than Earth, although its surface area is about the same as the land surface area of Earth.Like the other terrestrial planets—Mercury, Venus, and Earth— the Martian surface has been changed by volcanism, impacts from other bodies, movements of its crust, and atmospheric effects. The southern hemisphere of Mars is predominantly ancient cratered highlands, in contrast to most of the northern hemisphere which consists of plains and are much younger and lower in elevation. Mars also has polar ice caps that grow and recede with the change of seasons. Until recently, it was thought that Mars’ polar caps were made from carbon dioxide (dry ice) with only a small amount of water. Later observations indicated that the polar caps were mostly frozen water with a thin layer of carbon dioxide.
The highest known surface point on Mars is a huge volcano known as ‘Olympus Mons’. Olympus Mons, which means Mount Olympus, takes its name from the home of the ancient Greek gods.It is the largest volcano on Mars and likely the largest in the entire solar system. With a diameter of more than 500 km and a summit that towers 25 km over the surrounding plains, its volume is over 100 times that of Mauna Loa in Hawaii. The Tharsis plateau where Olympus Mons is located is home to three more volcanoes, each more impressive than the last.
The atmosphere is very thin, exerting less than 1 percent of Earth’s atmospheric pressure at the surface. Mars has an average surface temperature of about -23°C. Its atmospheric content includes 95% carbon dioxide, 3% nitrogen and 1.6% argon. There are also trace amounts of gases that have been produced from the primary constituents byphotochemical reactions, generally high in the atmosphere; these include molecular oxygen, carbon monoxide, nitric oxide, and small amounts of ozone.
Mars has two small moons, Phobos and Deimos. Both moons are irregular chunks of rock, roughly ellipsoidal in shape. Phobos, the larger of the two, revolves around Mars once every 7 hours 39 minutes. Phobos has been falling very slowly toward the planet at a rate of 10 km every century. A collision is estimated to occur in about forty million years. Deimos is smaller than Phobos and suffers the opposite fate. It moves in a more distant orbit, and tidal forces are causing it to move away from the planet.
The Search for Life
In 1877 Giovanni Schiaparelli developed a map of Mars based on observations that he made through his telescope near Milan, Italy. Schiaparelli’s maps contained lines criss-crossing the planet, which he termed “Canali”, the Italian word for channels. The word, erroneously translated into English as “canals” instead of “channels,” led to widespread speculation over whether the “canals” were constructed by intelligent beings.
The idea of intelligent life on Mars was not new and goes all the way back to the Middle Ages when it was widely considered that every planet had some form of life on it. The debate intensified when in 1996 NASA’s analysis of a meteorite, ALH84001, from the planet was discovered in Antarctica in 1984. The meteorite is estimated to be 4.5 billion years old and hit the Earth 13,000 years ago. The 4.2 pound rock contained microscopic structures similar to bacteria on Earth. In subsequent investigations, other scientists contested the evidence, demonstrating that each could be adequately explained by nonbiological processes or was not entirely consistent with what is known about microfossils and living microorganisms on Earth.
- Dark spots on the surface of the Red Planet were once interpreted as lakes or oceans, and some people even thought they could seen irrigation canals crisscrossing the surface.
- Mars has huge deposits of water underneath the surface, across the planet – in the form of ice.
- The Valles Marineris is the greatest gorge on any planet in the Solar System. It is an astounding 2,500 miles long and four miles deep. It was caused when volcanoes erupting around it tore up the land, leaving a huge valley.
- The Sun appears about half the size on Mars as it does from Earth.
- Mars’ red color is due to iron oxide, also known as rust. The metallic rocks on Mars are rusting.
- Mars has the largest and most violent dust storms in our entire solar system.
- Mars has no magnetic field, indicating that it does not have a molten metal core.
- NASA and ESA (European Space Agency) hope to land humans on Mars by 2035.
- Mars has all four seasons like that of Earth as its axis is tilted away from the Sun.