Mercury
Mercury is a small terrestrial planet nearest to the Sun. It was named after Hermes, the swift messenger of the Greek gods who is in the same status with the Roman God Mercury. Mercury is the fastest moving planet at an average speed of about 48 kilometres per second and it completes one revolution in 87.97 earth days. But it rotates on its axis very slowly by taking nearly 59 earth days to complete one rotation. The inner core of Mercury contains iron which covers 3,600 kilometres in diameter. The outer mantle of silicate rock is about 600 kilometres thick. The outermost surface is a crust of silicate rock pitted with craters due to the fall of meteorites. The largest crater, Caloris Basin, measures about 1,300 kilometres across. The craters may have been formed when a huge rock of extra large size hit the planet and due to the force mountains are formed around. The cooling and shrinking of the hot core of the planet for billions of years caused many ridges called rupes around the surface of the planet. The surface temperature in Mercury is extreme ranging from 173°C to 427°C. By night the temperature falls down quickly to icy cold. Mercury contains very small quantity of helium and hydrogen and traces of other gases. Due to the extremity in surface temperature and lack of oxygen existence of life in Mercury is impossible.
Mercury
Distance from the sun in km: 57.9 million Diameter at equator in km: 4878
Mass with respect to the earth: 0.056 (earth=1)
Gravity with respect to the earth: 0.386
Period of revolution: 87.97 earth days
Period of rotation: 59 earth days
Density: 5.42 g/cm³
Temperature: -173°C to 427°C
Satellites: Nil
Visit to Mercury
Mariner-10 was the only spacecraft that landed on Mercury. It was launched by the United States on March 29, 1974. Mariner-10 sent clear and close photographs of Mercury to the Earth. It also found that the magnetic field of Mercury is 1/10th when compared to our planet. Some scientists believe that this discovery the existence of iron in Mercury.
