Welcome To The Universe

An Infinite Guide To Everything Outside Our World

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The Dwarf Planet

There are oficially only eight planets in our solar system. According to scientists, there are hundreds of dwarf planets yet to be discovered and we already know of 44.

Pluto was discovered in 1930 by a fortunate accident. Calculations which later turned out to be in error had predicted a planet beyond Neptune, based on the motions of Uranus and Neptune. Pluto is usually farther from the Sun than any of the eight planets; however, due to the eccentricity of its orbit, it is closer than Neptune for 20 years out of its 249 year orbit. Pluto crossed Neptune's orbit January 21, 1979, made its closest approach September 5, 1989, and remained within the orbit of Neptune until February 11, 1999. This will not occur again until September 2226.


Pluto's Orbit

Pluto has the most eccentric orbit of all the planets in the solar system. Its orbit takes it to 49.5 AU (7.4 billion kilometers) at its farthest point from the Sun. And its orbit takes it as close as 29 AU (4.34 billion kilomters) to the Sun. It takes 249 years for Pluto to complete its orbit. This means that a single Pluto year is 249 earth years long.

Pluto's Atmosphere

Because the orbit of Pluto is so strange, Pluto is sometimes close enough to the sun for the ices on its surface to sublimate. Sublimation describes what happens when a frozen material changes to gaseous form. When Pluto comes close enough to the sun, the surface of solid Nitrogen sublimates to produce a substantial atmosphere with winds and clouds. Because the planet is so small, however, it does not have enough gravity to bind an atmosphere for very long. Thus Pluto's atmosphere is being rapidly produced and rapidly lost at the same time. This means that the atmosphere is not in equilibrium.

Pluto's moons

There are three known moons of Pluto. The largest, Charon, is proportionally larger, compared to its primary, than any other satellite of a known planet or dwarf planet in the solar system. The other two moons, Nix and Hydra, are much smaller.

Facts About Pluto

  • Pluto isn't a planet

  • Pluto has an atmosphere

  • Pluto hasn't cleared out its orbit - Although Pluto orbits the Sun and it's round, it's not a planet. And that's because Pluto hasn't cleared out its orbit of material. This was the reason that the International Astronomical Union chose to demote it from planet to dwarf planet in 2006.

  • Pluto, sometimes, is closer to the sun than Neptune.

  • There are 7 moons in our solar system that are larger than Pluto, including our own.

  • There is a spacecraft on its way to Pluto right now - NASA's New Horizons spacecraft is making its way to Pluto right now. The spacecraft launched in 2005, and its expected to reach the dwarf planet in 2015.


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