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So how come calling Pluto a planet is so goofy? page 4
Pluto: Not demoted, just reassigned, by Greg Black, of the University of Virginia

 Pluto, imagined here with its moon Charon, was demoted recently to dwarf planet. But there is more to the Plutonic 'neighborhood' than meets the eye.
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Date published: 5/16/2010


History offers us an interesting comparison. The first and largest asteroid, Ceres, was discovered on the first day of 1801. Many at first referred to this as a newly discovered planet between Mars and Jupiter. Roughly a year later a second asteroid was found, and then a third, then a fourth. In contrast, Pluto was discovered in 1930 and over 60 years passed before the second object in its region of the solar system was discovered. Almost 100 asteroids had been discovered in the 60 years after the first one was, and today we know of hundreds of thousands. But the lack of a second discovery soon after Pluto allowed enough time for its planet status to sink into our consciousness.

Until our understanding of planet formation improves and a solid scientific definition takes shape, the boundary between planets and dwarf planets will likely keep the official planet tally at eight. More discoveries await us in the distant parts of the solar system, and so the definition may need to be revised again.

As Juliet asked of Romeo, "What's in a name? That which we call a rose by any other name would smell as sweet." Scientists will continue to study Pluto, Ceres, and the other dwarf planets regardless of their official titles.

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Gregory Black is a planetary scientist at the University of Virginia.