Thursday, February 17, 2011

Astronomy Cast Ep. 194

Dwarf Planets

Dwarf planets have been debated over for years and years now.  Pluto has recently joined Eris and the astroid Ceres as a dwarf planet, after being known as a planet for several decades.  The demotion of Pluto was triggered by observations of Eris, which was a giant icy body, actually bigger than Pluto.  This also resulted in scientists reanalyzing the rules of being a planet.  The first rule is it must be round.  The second rule is it must be orbiting the Sun.  The third rule is it needs to have cleared out its own orbit.

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