While the speculations about the existence of life on Mars has once again put this planet into the spotlight, it continues to be our neighbor about whom we don't know much. Among the various little-known facts about this planet, one in particular is related to its natural satellites, i.e., the exact number of moons it has.
The Moons of Planet Mars
The fact that planet Mars has 2 moons may come as a surprise for many, as this planet is half the size of our Earth, which only has 1 moon. The speculation that planet Mars has moons surfaced long before Asaph Hall, Sr., actually discovered them in 1877. The famous German astronomer, Johannes Kepler had stated that Mars has 2 moons way back in the 17th century. However, his claims were more of assumptions which lacked scientific support. (These claims were based on the fact that the Earth had one moon and Jupiter was believed to have 4 moons.)
The 2 moons of planet Mars are named Phobos and Deimos, after the sons of Ares―the Greek God of War. While the former represents 'fear', the latter represents 'terror'. Martian moons were discovered by Asaph Hall, Sr. on August 12, 1877. Owing to their irregular shape, astronomers believe that these moons are actually captured asteroids. A comparison with the Earth's moon shows that the moons of Mars are different in several aspects.
Facts About Phobos and Deimos
Of the two, Phobos is the larger with a diameter of 14.1 miles, while Deimos has a diameter of 7.82 miles. The orbit of Phobos is located at a distance of 5826.59 miles from the surface of the planet, whereas that of Deimos is located at a distance of 14577.36 miles. Considering that the orbit of the Earth's moon is 238856.95 miles away from its surface, one can say that the moons of planet Mars orbit the planet at a very close range. While Phobos travels from west to east and takes 7 hours and 39 minutes to orbit planet, Deimos travels from east to west and takes 30 days, i.e., 1.2 Martian days to orbit it.
Recent observations have revealed that the gravity of planet Mars is slowing the orbit of Phobos. Going by the speed at which this is happening, Phobos will reach the Roche limit, i.e., the limit up to which a natural satellite can close in on its parent body and get disintegrated, within the next 15 million years. NASA has managed to collect some information about Phobos and Deimos, but a lot more is yet to be known.
NASA's efforts to facilitate low-cost planetary exploration has opened the realms of solar system for the mankind. With the premier organization in the field of space research continuing its space escapades, it won't be surprising if yet another fascinating attribute of Mars―or some other planet for that matter―surfaces sometime in the near future.