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Planets Going Backwards

23 Apr 2010, 19:22 UTC
Planets Going Backwards
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Tranisiting exoplanets are found by the light curve they create when passing in front of their parent star. Many of these planets are "hot Jupiters" orbiting very close to stars. Discovery of nine new transiting exoplanets was announced this week. When these results were combined with earlier discoveries, it was found that 6 of 27 exoplanets were orbiting in the opposite direction from the star's rotation. This challenges theories of stellar formation. Since Pierre Laplace, scientists have thought that solar systems condense from rotating disks of gas. As a result, the planets should orbit the same direction as the star rotates, as in our solar system. Unfortunately nature does not follow the theory. The very existence of "hot Jupiters" challenges the old theory. Orbiting so close to their parent star, these planets should boil away. The theory can not explain how planetary embryos can form from dust. If particles collide at orbital velocity they will ricochet rather than stick together. If these planets formed around Black Holes, they would follow the Black Hole's rotation independently of the parent star. The Black Hole would not suck these planets up, but would stabilize their centres. As a result Jupiter-size planets could exist ...

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