Fobos and Deimos
Monday, 24 February 2014 01:38

The satellites of Mars – Phobos and Deimos were discovered in 1877 by Asaph Hall. Both satellites is asteroids captured by a planet. Their size is: Phobos – 26.8х22.4h18.4 km, Deimos – 15х12.2x10.4 km (for comparison, the diameter of the moon 3476 km).  The satellites have a circular orbit and  rotate on a  average distance from the center of the planet: Phobos – 9400 km, Deimos – 23500 km (the average distance between the centers of the moon and the Earth 384467 km).

Every 100 years, Phobos is closing to Mars at 9 cm and approximately after 8-11 million years could fall to the planet or to break down into separate pieces in space. Surfaces of both satellites are covered with craters. Thanks to information obtained from "Phobos-2" there is the assumption that the third part of the satellite consists of a magnetic substance, "Phobos-2"  was found a leak of gas, but its nature is not clear. Period of rotation around the planet Phobos is 7 hours 39 min., Deimos 30 hours and 18 min. For one Martian day you can see Phobos for three times from Martian surface. Both satellites see on Mars from their orbits  one side.