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Planet X, the ninth planet from the sun, is discovered in Flagstaff, Arizona, by Clyde W. Tombaugh.
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11-year old Venetia Burney suggested the name Pluto to her grandfather, stating that the planet was similar to the Roman god Pluto. Her grandfather suggested the name to the professor of astronomy at the University of Oxford, where many loved the name and agreed unanimously upon it.
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Pluto moved inwards of Neptune's orbit for a brief amount of time. Pluto's orbit is highly eliptical, which allowed this to happen. During this period Neputune became the outer most planet, while Pluto was bumped up to planet #8.
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James Christy, while observing Pluto at the United States Naval Observatory, discovered that Pluto had a moon orbiting it. He named the moon Charon.
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Astronomers discover that Pluto, despite its lacking size, does indeed have an atmosphere.
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Pluto is now classified as a dwarf planet due to its size. It is still considered a planet because it orbits the sun, but it is not large enough to be considered a normal planet. Due to this, scientists and astronomers have a very clear subject for studying dwarf planets.
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Pluto and Charon were photographed by the Hubble Space Telescope when the two bodies were about 30 AU from Earth. The photos showed that Pluto and Charon are composed of different materials due to different colored surfaces.
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Due to new images from the Hubble Telescope, astronomers discover that Pluto has three moons, not just one.
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The New Horisons Space Craft, an unmanned probe intended to take photos of Pluto and its surroundings, was launched from Cape Canaveral after several delays.
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Pluto's two other moons are named Nix and Hydra by the International Astronomical Union.
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Astronomers meet in Prague to declare that Pluto is no longer classified as a planet under new guidelines. The solar system now contains eight planet.
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Astronomer Mark Showalter detects a fifth moon around Pluto through the Hubble telescope.
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The Hubble Telescope discovers a fourth moon orbiting around Pluto.
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The International Astronomical Union names the two newly discovered moons of Pluto, Kerberos and Styx.
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In 2015, Pluto is planned to reviece a visit from the New Horizons space craft launched in 2006. It will take photos of Pluto and its surroundings. The probe may gather new data which could possibly reclassify Pluto as a planet.
