Pluto: a Past Planet

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Eighty years ago, an astronomer by the name of Clyde Tombaugh, was comparing photographic plates from a special telescope created for the sole purpose of discovering a new planet he called, Planet X. He was to examine these photographic plates with a blink comparator to see if the object in the plate had shifted position. After a while he did discover that the object had shifted position, which meant that he had found Planet X, which today is called Pluto (History I: The Lowell Observatory in 20th century Astronomy). There was a time, eight years ago, where nine planets existed in the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. That all changed when it was voted, in 2006, that Pluto was to no longer be considered a planet due to the definition of a planet being rewritten. The new definition of a “planet” is “an object that orbits the sun and is large enough to have become round due to the force of its own gravity. In addition, a planet has to dominate the neighborhood around its orbit,” (Inman, 2006). Pluto obviously did not make the cut, unlike the other eight true planets that still exist today within the solar system. Pluto, now, is known as a dwarf planet. A dwarf planet is a celestial body that orbits the Sun and is also large enough to become round due to the force of its own gravity. Although it does have these assets, it cannot dominate the neighborhood around its orbit, such that Pluto’s moon, Charon, is about half the size of Pluto itself. A planet that dominates their neighborhood is able to scoop up asteroids, comets and other debris, which allows the planets elliptical path to be cleared along their orbits. Besides Charon, Pluto has four other moons: Nix, Hydra, Kerberos and Styx. The eight true planets are far larger than the moons that surround them. While Pluto does orbit the Sun, it is not a

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