Pluto has gravity.
Planets beyond Neptune . In 1978 , Pluto was conclusively determined to be too small for its gravity to affect the giant planets , resulting in a brief search for a tenth planet . Pluto . Pluto was discovered by Clyde Tombaugh in 1930 and was originally considered to be the ninth planet from the Sun . Like other Kuiper belt objects , Pluto is primarily made of ice and rock and is relatively small -- about one-sixth the mass of the Moon and one-third its volume .