While not much information is available about who discovered Mars, although many astronomers have shed light upon the theorization of the planets. The first astronomer to postulate that Mars and a few other bodies were planets was Nicolaus Copernicus. His theory published in 1543, made the astronomers widely consider the possibility of Sun being the centre of the solar system rather than the Earth. Another discovery was made by a Danish astronomer, Tycho Brahe, in 1576, who made accurate calculations of the position of Mars. A contradictory theory was established by Johannes Kepler that the orbit of the Mars was elliptical. However, in 1959, a strange feature was discovered by Christiaan Huygens, a Dutch astronomer, with the observations he made using his telescope, that feature was later known as Syrtis Major.
Mars is the fourth planet in the solar system at a distance of 227, 943, 824 km from the Sun. With a mass of about 6.4185 x 1023 kg, Mars takes 687 Earth days to orbit the Sun which means its year is twice that of the Earth. It has an equatorial diameter of about 6,805 km and easiest to observe when it in the opposite direction to that of the Sun in the sky. Because, it is then high in the sky and shows a fully lighted face. The best viewing occurs when the planet is closest to the Sun as well as to the Earth, because it is then that Mars is brightest and largest.
Telescopic observations revealed that Mars has a sparse and thin atmosphere mainly comprising carbon dioxide (95%). The rest of the atmosphere comprises nitrogen, hydrogen, oxygen, ozone and some noble substances like argon. Low-lying clouds and fogs are often observed within valleys or craters. Thin clouds are common at dusk. Most of the clouds seen are made of water-ice. The surface of Mars has two features; the northern hemisphere is relatively smooth with few craters whereas the southern part includes highlands that are heavily cratered compared to the Northern part. It has the highest mountains and the deepest canyons than any other planet. It also has the solar system's biggest volcanic mountain, Olympus Mons, which is more than thrice the height of Mount Everest. Mars has only 28% surface area as compared to the Earth. However, since Earth has about 70% water on its surface, both the areas are comparable. The topography, however, cannot be clearly seen and only variations in the opacity of atmosphere and changes in surface colour are observed.
The crust of the planet is mostly basalt rock. Its soil contains nutrients such as sodium, potassium, chloride and magnesium. The mantle is primarily composed of silicon, oxygen, iron and magnesium and is consistently a soft rocky paste. However, its solid core is composed of iron, nickel and sulphur.
Mars has two moons – Deimos and Phobos, which were discovered in 1877. They are very small; almost the sizes of small towns on Earth, irregular like the rock ellipsoidal in shape.
- Phobos: Phobos revolves around Mars once every 7 hours 39 minutes. It moves in an exceptionally close orbit at a mean distance of about 6,000 km.
- Deimos: Deimos revolves in an outer orbit than Phobos. They are not visible from all locations on the planet because of their small size, proximity to Mars, and near-equatorial orbits.
Mars was the Roman god of warfare, slaughter and agriculture. It protected those who fought for their communities, and stayed at home to raise crops for food. About 3,000 years ago, Babylonian astronomers as well as astrologers called the planet Nergal for their god of death and disease. The two moons of Mars, Phobos – Greek word for fear and Deimos – Greek word for terror were named after the two of the sons of Ares and Aphrodite.