Phobos and Deimos

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The Moons on Mars The planet Mars has two very small moons which were both discovered in 1877 by Asaph Hall. Asaph was determined to find a Martian moon but was becoming frustrated and decided to quit searching. His wife, Angelina, encouraged him to keep looking and the next night, August 12, 1877, he discovered Deimos and six nights later he discovered Phobos. They are among the smallest moons in the solar system. These two moons are also very dark and are thought to be captured asteroids. Phobos is 7.24 times larger than Deimos. It is named after the Greek god Phobos (which means “fear”). Phobos orbits 6,000 kilometers (3,700 miles) from Mars’ surface. No other moon orbits closer to its planet. Phobos’ greatest feature is a large crater which is 10 kilometers wide. It is almost half the width of the moon and was named Stickney which is Angelina’s maiden name. Phobos orbits Mars three times a day and is slowly moving closer to the moon. Phobos will eventually crash into Mars or break up and form a ring around the planet. Deimos (which means fear) was named after the Greek God Deimos who was the twin brother of Phobos. Deimos is the outer moon so it is further away from Mars and takes about 30 hours to orbit. It is small and lumpy and has lots of craters and is covered in dust and loose rocks. Although it has many craters it’s surface is much smoother than Phobos’ Deimos has an average radius of 6.2

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