Coyoty (coyoty) wrote,
Coyoty
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And then there were 12...

The International Astronomical Union will be voting next Thursday on a proposal to reclassify the planets, with the expectation in the astronomical community that it will be approved.  The proposal raises the number of known planets to 12.

The proposal establishes two rules as the basis for qualifying as a planet: that the object must orbit a star without being a star itself, and that it must have enough mass for its gravity to pull it into a spherical shape. Under these rules, the newly qualifying objects would be the asteroid Ceres, and in the new "pluton" classification, Charon and Xena.

The pluton class of planets would be created to satisfy the dispute over whether planet-sized Kuiper Belt objects like Pluto actually qualify as planets.  The discovery of Xena being larger than Pluto had complicated the argument, because Xena couldn't justifiably be ruled out as a planet if Pluto stayed classified as one.  Because it seems the fight to save Pluto's status would never end, it's more politically expedient for it to found a new classification, under which Charon and Xena will qualify.

Because of Charon's size in relationship with Pluto, it would be reclassified from a moon to a planet, as part of a binary planet system.  I expect this would give support to those who argue that Earth's moon should be reclassified as a planet because of its size in relationship with Earth.

http://news.bbc.co.uk/2/hi/science/nature/4795755.stm

Tags: ceres, charon, classification, planets, plutons, xena
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