Who discovered Pluto, and when?

Clyde Thombaugh, an American astronomer, discovered Pluto on February 18, 1930. Although we think of it as the planet farthest from the Sun, Pluto actually spends 20 years of its 249-year orbit closer to the Sun than Neptune’s distance. Of late, Pluto made its closest approach to the Sun during 1989 and will remain within Neptune’s orbit until March 14, 1999.