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Nothing but the Facts About Pluto

written by: KBunn•edited by: Jason C. Chavis•updated: 4/6/2011

Pluto, once considered the smallest planet in our solar system, was downgraded to a dwarf planet in 2006, 76 years after its discovery in 1930. The downgrading of Pluto shrouded it in controversy and has made it a popular subject for astronomers worldwide. Read below for more facts about Pluto.

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    The Facts


    1) Position in the Solar System: 10th largest body orbiting the sun; it was the 9th and farthest planet from the sun before it was downgraded.

    2) Closest Distance to the Sun: Perihelion: 4.44 trillion km or 2.76 trillion miles

    3) Furthest Distance from the Sun: Aphelion: 7.38 trillion km or 4.58 trillion miles

    4) Minimum Distance to Earth: 4.28 billion km or 2.66 billion miles

    5) Plutonian Day: 6.39 Earth days

    6) Plutonian Year: 248 Earth years

    7) Axis Tilt: 123 degrees

    8) Orbital Inclination to Ecliptic: 17.14 degrees

    9) Orbital Eccentricity: 0.249

    10) Diameter: 2,390 km or 1,485 miles

    11) Mass: 1.3 x 10^22 kg

    12) Gravity: .58

    13) Escape Velocity: 4.570 km/h or 2,840 mph

    14) Temperature Range: -233C to -223C or -387F to -369F

    15) Atmospheric Composition: Made up of methane, carbon monoxide, and nitrogen

    16) Number of Moons: 3 (Charon, Hydra, and Nix)

    17) Ringed System?: No

    18) Magnetic Field?: Unknown

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    Pluto Amazing Facts!

    1. Pluto was found in 1930 by Clyde Tombaugh, an American astronomer. In 2006 it was downgraded from the 9th planet to a dwarf planet because it does not clear the path of surrounding debris in its orbit (one of the three requirements of a planet). This was heavily promoted by Dr. Neil deGrasse Tyson.

    2. No spacecraft have ever visited Pluto, and its position makes it hard to study anywhere except from Earth's surface. On January 19, 2006, though, NASA launched "New Horizons," a mission that will explore not only Pluto but the Kuiper Belt as well.

    3. Pluto and Charon (one of its moons) are locked into the same gravity that keep them in identical orbit, facing the same sides of each other at all times. Charon, like our moon, always presents the same side to Pluto, but unlike Earth, Pluto always presents the same side to its moon, Charon, as well.

    4. Venetia Phair, an 11 year old girl from England, suggested the name Pluto for the now dwarf planet. It is also called a Plutoid.

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    Pluto and Charon

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    Image Source

    Pluto. (Supplied by NASA; Public Domain;