Generally Pluto is the ninth planet from the Sun. Periodically it switches places with Neptune and becomes the eighth planet from the Sun. This switch occurs because Pluto’s orbit is very narrow and stretched out causing  its path to go between Neptune and the Sun. The last time this happened was from February, 1979 to February, 1999.

Its small size and distance from the Earth makes Pluto mysterious. Pluto was discovered in 1930 by Clyde W. Tombaugh, an American astronomer. During this time period, astronomers were looking for a missing Planet X. The search began when scientists realized that Neptune had an unusual orbit. Astronomers thought a large planet  with a strong gravitational pull existed beyond Neptune. Pluto is so tiny that it has little affect on Neptune’s orbit. In fact, some scientists dispute Pluto’s status as a planet. The International Astronomical Union(IAU) is the organization that recognizes space objects. According to its requirements, Pluto qualifies as a planet.

Pluto was named for the Roman god of the underworld. In 1978, Pluto’s moon was discovered. It was named for Charon, the ferryman of the underworld. Charon is more than 1/2 the size of Pluto. Some scientists consider Pluto and Charon to be a double planet. The center of gravity of the two bodies is located in space rather than on the planet, Pluto. The planet and its moon rotate in a spiral around a center of gravity that is between them.

Pluto is the only planet that has not been visited by a probe. Scientists think the planet is made of rock and ice. It is believed to be the coldest planet in our solar system. A mission to Pluto is being planned by the Jet Propulsion Laboratory(JPL). Planned launch date is 2004. Pluto should be reached around 2010. Until the probe results are received, Pluto remains a mystery.

Pluto Facts

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