17 January
1997: On 17 January 1997, Clyde W. Tombaugh died.
Tombaugh was an American astronomer who discovered the planet Pluto in 1930, the only planet discovered in the twentieth century, after a systematic search instigated by the predictions of other astronomers.
Tombaugh made his discovery at Lowell Observatory in Flagstaff, Arizona, USA. He also discovered several clusters of stars and galaxies, studied the apparent distribution of extragalactic nebulae, and made observations of the surfaces of Mars, Venus, Jupiter, Saturn, and the Moon.
