Asaph Hall III (1829-1907), US astronomer. Hall studied mathematics and geometry in New York, moving into astronomy when calculating planetary orbits at Harvard College Observatory. His most famous discovery, that of the moons of Mars (Deimos and Phobos), was made in 1877 while working at the US Naval Observatory. Hall's awards included the Lalande Prize of the French Academy of Sciences (1878) and the Gold Medal of the Royal Astronomical Society (1879). A lunar crater and an asteroid have been named in his honour. This photograph, part of the Brady-Handy Collection, dates from between 1865 and 1880.