From a distance of only 9,670 kilometers, MGS resolves details as small as 36 meters on the rocky body. The aligned rows of pits and grooves are a direct result of an ancient impactor — the crater Stickney, not seen in this view, is the most pronounced scar from the collision. The moon itself is small by Earth standards. It is only 27 by 22 by 18 kilometers and is about 0.006 times the size of Earth's Moon. Phobos orbits Mars about once every eight hours, three times per Martian day.