Cool Deimos Facts and Images

Deimos is the smaller and more distant of the two Martian moons, with an average diameter of 8 miles (13 kilometers) and an orbit that is 12,400 miles (20,000 kilometers) away, on average. On the surface of Deimos, the acceleration of gravity is less than 0.1 percent that of Earth. But like Phobos, Deimos has been able to develop landforms, like craters and rims, similar to those found on larger objects.

Deimos' craters lack the grooves and ridges seen on Phobos. Typically when a space rock hits another object, surface material is thrown up and out of the resulting crater, scientists say. The material usually falls back to the surface surrounding the crater.

However, these "ejecta deposits" are not seen on Deimos, while they do appear on Phobos. Researchers speculate that Deimos' gravity is so low that the ejecta escaped to space. But still there seems to be that coating of dust.

Of the two Martian moons, Deimos has a much smoother surface. This may be because the deposit of dust and other fine material continued after most of the moons impact craters were formed.

From Mars, Deimos is so far away and so small that it would appear as no more than a very bright star in the night Martian sky. More about Deimos in our Reference Section.

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