Pluto, minor-planet designation 134340 Pluto, is the largest object in the Kuiper belt, and the tenth-most-massive body observed directly orbiting the Sun. It is the second-mostmassive known dwarf planet, after Eris. Pluto is composed mainly of rock and ice and is relatively small. It has an eccentric and highly inclined orbit that takes it from 30 to 49 AU (4.4â€“7.4 billion km) from the Sun. This causes Pluto to periodically be closer to the Sun than Neptune. As of 2014, it is 32.6 AU from the Sun.
Pluto was discovered in 1930. It was originally classified as the ninth planet from the Sun. However, However, its status as a major planet was rejected. The name Pluto was proposed by Venetia Burney, an eleven-year-old schoolgirl in Oxford, England.
The understanding that Pluto is only one of several large icy bodies in the outer Solar System induced the International Astronomical Union (IAU) to define formally what it means to be a "planet" in 2006. According to this definition Pluto was excluded as a main planet and reclassified as a member of the new "dwarf planet" category (and specifically as a plutoid).
THE END By Team 4