Phobos: Mars's Doomed Moon

space · mars · moons

Tiny and Weird. Phobos is much smaller than Earth's moon, shaped like a lumpy potato about 16 miles across. It has deep craters from asteroid crashes that pummeled it over billions of years.

Falling Toward Mars. Unlike our moon, Phobos is spiraling closer to Mars every year. In about 30 to 50 million years, it will either crash into the planet or break apart into a ring system.

Discovered Recently. Even though Phobos has existed for billions of years, humans didn't spot it until 1877 when American astronomer Asaph Hall first saw it through a telescope.

Named After Fear. Phobos takes its name from an ancient Greek god of fear and panic, the twin brother of Deimos (the other Martian moon) and son of Ares, the god of war, whose Roman name is Mars.

Rising and Setting Strangely. From Mars's surface, Phobos rises in the west and sets in the east, the opposite of how our moon moves across Earth's sky.