On August 18, 1877, the Martian moon (natural satellite) Phobos was discovered. It is one of the two Martian moons, with the other named Deimos. Namely, the names Phobos and Deimos are taken from Greek mythology, and they represent the twin gods, the sons of Ares (Mars) and Aphrodite (Venus), where Phobos means fear, and Deimos horror.
Phobos and Deimos are very small satellites and are irregularly shaped. Phobos is approximately ellipsoidal in shape, and its longest dimension is about 26.8 kilometers. Its total area is about 610,000 hectares. Despite being relatively small compared to the Earth’s Moon, Phobos still has a mass of over 10 trillion tons.
Phobos was discovered by the American astronomer Asaph Hall, and it is interesting that the largest crater on Phobos – Stickney (it was her maiden name) is named after his wife. It is a crater that is relatively very large, so that it occupies a significant part of the surface of Phobos. Phobos’ orbit is relatively close to the surface of Mars, at an altitude of about 6,000 kilometers (this is lower than any other known moon in the solar system). As a result, it takes a short time for that satellite to orbit Mars, only 7.6 hours.