Artist's impression of the planet Pluto (foreground) the nineth & smallest planet of our solar system & its close satellite (moon) Charon. Discovered in 1930 at the Lowell Observatory by Clyde Tombaugh, Pluto has a 248 year orbit around the sun. The satellite Charon was discovered in 1977 by J. Christy. Some doubt exists whether Pluto should be regarded as a true planet; it might be more appropriate to describe it and Charon as comprising a double asteroid. Pluto is too faint to be observed by small telescopes and no surface details may be seen; spectroscopic data indicates that its surface is covered in a layer of methane ice.