Astronomy basics > Fast Facts: Dwarf planet, Pluto

Fast Facts: Dwarf planet, Pluto
Age About the same age as the Sun: 4.5 billion years
Location Solar system
Avg. distance from the Sun 5,914,000,000 km (3,674,000,000 miles)
Diameter 2340 km (1454 miles)
Mass 1.27 x 1022 kg
Orbital period around the Sun 247.7 Earth years (90,410 Earth days)
Number of moons Five: Charon is Pluto's largest moon, discovered in 1978. In 2006, two smaller moons (P2 and P3) were discovered by the Hubble Space Telescope. They were confirmed by other observations and later named Nix and Hydra. In 2011, a fourth moon, P4, was discovered in Hubble data. In 2012, nine separate sets of Hubble observations uncovered a fifth moon, P5.
Distinguishing features Pluto was the smallest planet until August 2006, when the International Astronomical Union reclassified it as a dwarf planet. Its composition and atmosphere are unknown but it is likely composed of rock, ice, and frozen gases. Its atmosphere is mainly nitrogen with a little carbon monoxide and methane. Pluto’s orbit is more elliptical and more inclined than the orbits of the eight solar system planets. The icy dwarf planet is not massive enough to clear debris from its orbit, a key reason why it is not a planet.
Pluto
A "map" of the surface of tiny Pluto

Astronomy basics > Fast Facts: Dwarf planet, Pluto