Phobos and Deimos


Phobos has an orbit that is below Mars synchronous orbit radius but because it orbit around Mars so fast however, it rises in the west and sets in the east at a speed of twice a day. Also, because it is so close to Mar's surface it can not be seen about the horizon at any point on mars meaning , Phobos is doomed. This being said for the reason that its orbit is below synchronous altitude and tidal forces are lowering its orbit at at a current rate of 1.8 meters a century. It is said in about 50 million years Phobos will either (1) crash onto the surface of mars or (2) most likely break up into a ring.


  It is said that Deimos came to orbit around Mars because it was asteroid that was probably perturbed by Jupiter. If you look at Mars from Deimos, it appears 1,000x times larger and 400x times brighter than a full moon seen from Earth. Also, from Mars  Deimos would appear almost like a star-like object to the naked eye and at its bright  cycle, it is about as bright as Venus from the Earth and at it's first and third quarter it woudl be as bright as Vega.  It also takes 1.2648 days for Deimos's phases to complete one of it's cycles/course.
  Deimos's orbit around Mars is slower than Phobos's orbit, meaning that it rises in the east and sets in the west. Also, Deimos’s orbit is relatively close to Mars and has only a very small inclination to Mars’ equator, it cannot be seen from Martian latitudes greater than 82.7°.

  *However, the Sun-synodic orbital period of Deimos of about 30.4 hours exceeds the Martian solar day ("sol") of about 24.7 hours by such a small amount that 2.7 days elapse between its rising and setting for an equatorial observer.