What do we know about satellites of Mars?
When address science history, some events make impression of almost mystical … Here, for example, history of opening of satellites of Mars - opening it was predicted! And it is predicted three times...
the First of these predictions was absolutely unscientific: J. Swift in the book “Gulliver`s Travel“ writes about two satellites of Mars (that prompted to the writer such thought - it is only possible to guess).
Other prediction belongs to Johann Kepler and it was based on a mistake … more precisely, on two mistakes. At that time - thanks to Galileo Galilei - it was already known of four satellites of Jupiter and, of course, of the only satellite of Earth - the Moon. From this I. Kepler drew a conclusion that the number of satellites at planets increases in a geometrical progression in process of removal from the Sun - therefore, at their Mars has to be two … And confirmation to that was found … at the same G. Galilei.
The matter is that G. Galilei, having seen in the telescope two foggy spots of Saturn on each side, assumed that it is satellites too, but in it it was not confident (actually that there were rings of Saturn) and therefore made record about it in encrypted form as “The highest planet threefold I observe an anagram of the Latin phrase“. I. Kepler deciphered this “message“ of G. Galilei as “Hi to you, twins, Mars generation“. Mentions two “moon“ of Mars, “the terrestrial astronomers escaping eyes“, and F. Voltaire in the philosophical story “Mikromegas“ … But the genius is also mistaken ingeniously: in 1877 satellites of Mars were open - them really it appeared two!
We will get acquainted closer with the “twins“ named Phobos and Deymos. Contrary to I. Kepler, them do not consider “Mars as generation“ - i.e. it is supposed that they were not created together with the planet … Very much both satellites are similar to one of types of asteroids that suggests an idea that Phobos and Deymos - the former asteroids taken by gravitation of Mars. However, there is also other hypothesis: satellites once “broke away“ from the planet at collision with some other object (the fact that orbits almost completely coincide with the plane of the planet will be coordinated with it, in particular).
Satellites of Mars are not in the flower of beauty (one researcher compared them to potatoes), but they managed “to cause a stir“ in another: they one of the smallest satellites in Solar system. Deymosu (an ellipsoid of 15 by 12 by 11 km in size) concedes only Leda - one of satellites of Jupiter with a diameter of 10 km. Also Phobos - 27 km is small.
But though we also called Phobos and Deymos “twins“, in some parameters of distinction between them it is more, than similarities. It is possible even to tell that they are opposite. So, for example, Phobos rotates around Mars so quickly that in days (certainly, Martian) manages to bypass three times and 78 more degrees, Deymos zhe - on the contrary - moves slowly, its cycle time is slightly more than Martian days. And though they move in one direction, for the observer who is on Mars Phobos would ascend in the West, and Deymos zhe - exactly the opposite would come in the east.
And even the future of satellites is opposite: Deymos Phobos seeks “to escape“ from Mars (and finally it will manage it), on the contrary - approaches the planet on 2 meters every century. Will come to an end in the fact that it will fall to Mars - accident will be grandiose, and Mars which lost both satellites in exchange will get a magnificent ring from dust …
However, we it will not see any more - it happens through 50 million years.