(1) When Clyde Tombaugh discovered it in 1930, astronomers welcomed Pluto as the long-sought "Planet X" whose gravity would account for unexplained peculiarities in the orbit of Neptune.

(2) In 1930, astronomer Clyde Tombaugh discovered the dwarf planet Pluto while looking at photographs of the night sky.

(3) American astronomer Clyde Tombaugh announces discovery of Pluto at Lowell Observatory.

(4) In 1930, a young astronomer named Clyde Tombaugh found Pluto.

(5) Clyde Tombaugh was too poor to go to college, but he got a job as an assistant at Lowell Observatory, and eventually he discovered the planet Pluto !

(6) Discovered in 1930 by the American Clyde Tombaugh, the icy rock of Pluto has traditionally been considered the ninth planet, farthest from the sun in the solar system.

(7) There are too many stars, comets and asteroids for only professional astronomers to keep an eye on, so we shouldn't be surprised that Pluto was spotted by an amateur, Clyde Tombaugh, in 1930.

(8) February of 2010 marks the 80th anniversary of the discovery of Pluto by American astronomer Clyde Tombaugh.