The International Astronomical Union, meeting in Prague, agreed on a proposal to define what exactly makes up a planet – and in so doing, trimmed our solar system to eight “classical” planets, unceremoniously giving Pluto the boot.
The new rules say that not only must a planet orbit the sun and be large enough to assume a generally round shape, but that it must “clear the neighborhood around its orbit” – something not done by Pluto because its orbit periodically overlaps that of Neptune (no word on why Neptune makes the cut with this happening – apparently this road doesn’t travel in both directions).
So distant Pluto, which had a planetary run for 76 years or thereabouts, drops to a new status of “dwarf planet”, along with the asteroid Ceres, which also was briefly a planet in the 1800s before it, too, was demoted, and 2003 UB313, an icy object slightly larger than Pluto affectionately known as Xena. Pluto’s largest moon, Charon, which had been in line for planetary desgination as recently as a week ago, is now in line for exactly bupkis.
Comments
One response to “Pluto, We Hardly Knew Ye”
This change is just plain silly, as remarked on in Chad’s entry. How does Neptune rate if it fails the same test? You can’t have it both ways. Some losers in the astronomical community just don’t like that Pluto is a planet (albeit a puny one). Also, why are we calling an asteroid a dwarf planet? If it’s an asteroid, call it an asteroid.