Phobos is the larger of the two moons on Mars and the closest to the planet, with Deimos being the other moon. Both were discovered by the American astronomer Asaph Hall in 1877. Phobos is a small, irregularly shaped satellite with an average radius of 11 kilometers. It always presents the same face to Mars, due to the tidal anchorage exerted by the planet. It orbits about 6,000 kilometers from the Martian surface, making it the closest satellite to your planet in the Solar System.
