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The great planet debate

New suggestions for defining a planet would put Pluto and many other objects back on the list.

6:22pm, August 15, 2008

LAUREL, MD. — Ask planetary scientist Mark Sykes where NASA’s Dawn spacecraft is headed, and he will say it is on its way to the largest asteroid and the smallest planet.

Dawn launched in September 2007 and is scheduled to rendezvous with the asteroid Vesta in 2011 and then with the dwarf planet Ceres in 2015.

But a dwarf planet is not a planet — at least

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