Mars At its closest approach to Earth, Mars is the fourth brightest object in the sky after the Sun, the Moon and Venus. At approximately 142 million miles, 53% further than Earth, Mars is the fourth planet from the Sun, which it orbits every 1.88 years. It has two small satellites, Phobos and Deimos, which orbit close to the planet.
The distinct red colour of Mars, observed even by eyesight, results from its heavily oxidised surface. Its thin atmosphere (the pressure is only 0.6 % of Earth) is comprised mainly of carbon dioxide with small amounts of nitrogen, argon and oxygen. The atmosphere produces a greenhouse effect but only raises the temperature slightly. The average temperature on Mars is about –55ºC but the planet`s surface temperature ranges from –133ºC at the winter pole to 27ºC on the daylight side during summer.
Mars has some of the most varied and interesting terrain of any of the planets in the solar system. For example, Olympus Mons at 24 kilometres above the surface is the largest volcanic structure anywhere in the solar system. Its base is more than 500 kilometres in diameter and is rimmed by a cliff averaging 6 kilometres in height. Valles Marineres is a 7 kilometre deep, 4,000 kilometre long fissure that stretches a quarter of the circumference of Mars and, again, is the largest in the solar system. The polar regions of Mars are covered in ice. The northern hemisphere is less cratered than the southern which consists of relatively recent lava flows, leading scientists to believe that this surface is younger. Physical features closely resembling shorelines, gorges, riverbeds and islands suggest that large rivers once flowed on the planet.
The Orbit of Mars
Mars moves in a more elliptical orbit then the Earth, so that its distance from the Sun can range from 208 million kilometres at perihelion to 248 million kilometres at aphelion. This orbit is responsible for the significant differing surface temperatures mentioned earlier. The closest approaches to the Earth occur when Mars is both at perihelion and opposition at about the same date. Then its distance from the Earth, as in August 2003, can be as little as 56 million kilometres. When opposition occurs with Mars at aphelion the distance increases to 100 million kilometres. Through a telescope Mars appears nearly twice as large at perihelic opposition than at aphelic oppostion. Unfortunately for northern observers, perihelic oppositions occur in August and always put the planet well south of the equator and rather low in the sky. A winter opposition puts Mars higher in our sky but, being further from the Sun and Earth, it appears smaller showing less detail.
1960 saw the first attempted Mars missions. Several Russian and American attempts failed until in November 1964, Mariner 4 passed the planet, discovered its cratered surface, and returned 22 TV pictures. The first Mars landings were by two Russian craft during May 1971. During the same month NASA put the first artificial satellite into orbit around Mars, and took pictures of the entire surface. In 1976 two Viking craft landed on the surface and collected large quantities of quality images and data. In September 1997 NASA`s Mars Global Surveyor (MGS) entered orbit around the planet and is still providing high resolution images. A further six missions have been sent since then with three orbiters and two landers currently in operation (including the Mars Express which hosted the unfortunate British Beagle II lander with which contact was lost after landing at Christmas 2003) sending back a wealth of photographs and information. In all there have been nearly 60 attempted missions to Mars with at least another 10 planned between now and 2016. The eventual Russian and American aim is to send a human crew.
Face on Mars Before space exploration, astronomers thought they saw straight lines criss-crossing the surface, leading to the popular belief that these were irrigation canals. Late 19th and early 20th century fiction gave credence to life on Mars, later dispelled. The Face caused a further controversy and was thought to be a symmetrical object in the form of a humanoid face that could only have been `built` by intelligent beings. Now observed for more than 30 years, this crumbling edifice is now seen as native geology rather than carved by natives.
However, there are currently other strange, unexplained, curious anomalies in recent images that, some say, space agencies seem reluctant to publish or explain.
Some of these images include photographs showing what appears to be translucent tube-like ribbed structures. They appear to be partially covered by the surface terrain and partially exposed. Conspiracy theorists think they are structures built by aliens however scientists contend they are simply lava tubes near or on the planet’s surface.
In Roman mythology, Mars was the god of war and son of Jupiter. Mars fathered Romulus, the legendary founder of Rome, and was, therefore, himself regarded as the father of the Romans.
In terms of astrology, Mars is the planet of willpower, energy, sexual drive and aggressive behaviour. In its positive form, Mars gives a person great energy, the will to carry out daunting tasks, endurance, a strong sexual drive, an adventurous nature and an independent-minded and assertive personality. In its negative form, Mars instils recklessness, impatience, a quick temper and an argumentative and overly aggressive personality.