Moons of MarsIn 1877, American astronomer Asaph Hall discovered the two moons of Mars, which he named Phobos and Deimos. In Greek mythology, these are the sons of Ares (Mars) and Aphrodite (Venus). Deimos is Greek for "panic" and phobos is Greek for "fear". These moons are composed of carbon-rich rock like C-type asteroids and ice. But their densities are so low that they cannot be pure rock. They are more likely composed of a mixture of rock and ice. Both are heavily cratered. They are probably asteroids perturbed by Jupiter into orbits that allowed them to be captured by Mars. There is some speculation that they originated in the outer solar system rather than in the main asteroid belt.[Image: Moons of Mars images by Viking Orbiter 1977; shown at the same scale] |
