THE NEW SOLAR SYSTEM
Ancient observers watched the celestial bodies move regularly against the starry sky. Those movement inspired the word "planet," from the Greek for wanderer. The ancients named and honored the sun, moon and five planets that they believed revolved around Earth; Mercury, Venus, Mars, Jupiter and Saturn.
In the 16th century, Nicolaus Copernicus disputed the notion that most heavenly bodies orbited Earth with his proposal of a heliocentric universe. Uranus was discovered-rather, it was identified as a planet and not stars- by British astronomer Willian Herschel in 1781. In 1846, German astronomer William Herschel in 1781. In 1846, German astronomer Johann Gottfried Galle Identified Neptune. Tiny Pluto turned up on a photographic plate at Arizona Lowell Observatory in 1930.
The list of our solar system nine planets was challenged in 2005 when the discovery of large body in the Kuiper belt reopened rigorous discussion among astronomers about planetary classification.
The International Astronomical Union (IAU) met in Prague in August 2006 and, though only a fraction of its members were present for the vote, arrived at a new definition of a planet. The effect of these decision changed the lineup of our solar system, leaving the number of planets an "Elite eight" The IAU classified Pluto with two other smallish as dwarf planets. Ongoing discoveries no doubt will continue to change our view of the solar system.
MORE NEW PLANETS?
The definition of a planet and the list of the planet in our solar system may keep changing. At one point during the great planetary shake up of 2006, the IAU briefly proposed a definition that would have have included more than a hundred objects belonging to the category of "planet".
Ceres, Pluto, Haumea, and Eris are dwarf planets; the latter t
hree and there moons are further designated as plutoids, dwarfs planets found beyond Neptune in the Kuiper belt. Haumea, officially recognized in 2008, is the nearest plutoids. This egg shaped dwarf planet spins rapidly, completing one rotation every hours.
hree and there moons are further designated as plutoids, dwarfs planets found beyond Neptune in the Kuiper belt. Haumea, officially recognized in 2008, is the nearest plutoids. This egg shaped dwarf planet spins rapidly, completing one rotation every hours.
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