Asaph Hall (Goshen, 1829 / Annapolis, 1907) was an American astronomer. With little academic training, he was self-taught and in 1857 he went to work as an assistant astronomer to William C. Bond at the Harvard Observatory, then moving on to the Naval Observatory in Washington. In August 1877, durant a great opposition, 6 days apart, he discovered the two satellites of Mars, Deimos (on the 12th) and Phobos (on the 18th). He also discovered the rotation period of Saturn and calculated the mass of Mars and other planets.
