The Planet Debate
HOW MANY PLANETS? After a week of fractious debate, astronomers at the General Assembly of the International Astronomical Union (IAU) in Prague have settled on a new definition of "planet," and they're voting on it this morning. If approved, the solar system would have 11 planets--8 classical planets and 3 dwarf planets.
The classical planets would be Mercury, Venus, Earth, Mars, Jupiter, Saturn, Neptune and Uranus. The dwarf planets would be Ceres, Pluto and 2003 UB313.
According to the new definition, to be a planet, (1) a world must have enough gravity to gather itself into a ball and (2) it must orbit the sun. If it has "cleared the neighbourhood around its orbit," then it is a classical planet. If it has "not cleared the neighbourhood around its orbit," then it is a dwarf planet.
So, e.g., mighty Jupiter, which circles the sun supreme in its own orbit, would be a classical planet, while Ceres, which shares its neighborhood with thousands of asteroids, would be a dwarf planet.
The vote is underway. Stay tuned for updates.
http://www.spaceweather.com/
The classical planets would be Mercury, Venus, Earth, Mars, Jupiter, Saturn, Neptune and Uranus. The dwarf planets would be Ceres, Pluto and 2003 UB313.
According to the new definition, to be a planet, (1) a world must have enough gravity to gather itself into a ball and (2) it must orbit the sun. If it has "cleared the neighbourhood around its orbit," then it is a classical planet. If it has "not cleared the neighbourhood around its orbit," then it is a dwarf planet.
So, e.g., mighty Jupiter, which circles the sun supreme in its own orbit, would be a classical planet, while Ceres, which shares its neighborhood with thousands of asteroids, would be a dwarf planet.
The vote is underway. Stay tuned for updates.
http://www.spaceweather.com/
posted by Dani @ 7:10 AM
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