Phobos & Deimos
Mars has two very small moons. They are so small that Phobos, the largest and innermost one, is 28 by 20 km and Deimos, the smallest and outermost, has a diameter of 8 km. Compared to our moon they would look one third of it's size from the Martian surface.The larger and innermost one called Phobos, orbits the planet in an orbital period of .319 days or three times a day, and is 9,270 km above the Martian surface. The smallest and outermost moon of Mars, called Deimos orbits the planet in an orbital period of 1.263 days and is 23,460 km above Mars' surface. All in all you might see that these moons are significally small.
When and how were they discovered?
Phobos and Deimos were discovered in August 12, 1877 by Asaph Halph with the help of his telescope and his wife at the U.S Naval Observatory, where Hall was an astronomer.
How did this moons form?
As Scientist say, the most likely theory is that the Phobos and Deimos were not formed with the planet, but are captured asteriods. Researchers believe this because of the moons particularly small size, cratered surfaces and the fact that Mars is reasonably close to the asteriod belt of our solar system.
Where did their names come from?
Phobos and Deimos were named after Mars' mythological attendants. Phobos meaning fear and Deimos meaning panic.