Portrait of Giuseppe Piazzi (1746-1826), Italian astronomer. Piazzi was a monk, who only took an interest in astronomy from his middle age. In 1801 he discovered the first known asteroid, Ceres, but lost sight of it after only three observations. A period of illness left him unable to observe for a while, but Ceres was rediscovered by Olbers following a remarkable calculation of the orbit by Gauss. In 1814, Piazzi published a catalogue of 7647 stars visible from Sicily, and showed that proper motion was a property of all stars, not just those closest to Earth. The 1000th asteroid found was named Piazzia in his honour.