Planet Mug PLUTO

PLUTO This is the most accurate natural color images of Pluto taken by NASA's New Horizons spacecraft in 2015. Pluto is a dwarf planet in the Kuiper belt, a ring of bodies beyond the orbit of Neptune. It was the first object discovered in the Kuiper belt and remains the largest known body in that area. After Pluto was discovered in 1930, it was declared the ninth planet from the Sun. However, beginning in the 1990s, its status as a planet was questioned following the discovery of several objects of similar size in the Kuiper belt and the scattered disc, including the dwarf planet Eris, leading the International Astronomical Union (IAU) in 2006 to define the term planet formally—excluding Pluto and reclassifying it as a dwarf planet. Pluto is the ninth-largest and tenth-most-massive known object directly orbiting the Sun. It is the largest known trans-Neptunian object by volume but is less massive than Eris. Like other Kuiper belt objects, Pluto is primarily made of ice and rock and is relatively small—one-sixth the mass of the Moon and one-third its volume. It has a moderately eccentric and inclined orbit, ranging from 30 to 49 astronomical units (4.5 to 7.3 billion kilometers; 2.8 to 4.6 billion miles) from the Sun. Therefore, Pluto periodically comes closer to the Sun than Neptune. Still, a stable orbital resonance with Neptune prevents them from colliding. As a result, light from the Sun takes 5.5 hours to reach Pluto at its average distance (39.5 AU [5.91 billion km; 3.67 billion mi]). Pluto has five known moons: Charon (the largest, whose diameter is just over half that of Pluto), Styx, Nix, Kerberos, and Hydra. Pluto and Charon are sometimes considered a binary system because the barycenter of their orbits does not lie within either body. Pluto and Charon are tidally locked.