Will Pluto be declassified as a planet and get lumped with the Kuiper Belt Objects?
Will ‘Xena’ (aka 2003 UB313) and Sedna become the 10th and 11th planets? (Eddie Astro, Somewhere, World) Poor icy Pluto is no longer a planet. He plies a lonely path mostly beyond Neptune. Actually, not exactly lonely. He has at least 100 little Pluto-like objects for company, moving in Pluto-like orbits a ‘plutino’ family. Drawing courtesy of the Luna and Planetary Institute, NASA. On Aug. 24, the IAU decided on new rules for planets; see sidebar. Your Pluto guess was right. Pluto got busted because much bigger Neptune dominates Neptune’s region of space, and, consequently, strongly influences Pluto’s orbit. See their orbits, drawings courtesy of Nine Planets (a misnomer, these days). For about 20 years out of his 248-year orbit, Pluto is closer to the Sun than Neptune. This wanton infringement of Neptune’s space has cost him, though. He doesn’t “clear the neighborhood around its orbit”, one of the three criteria for planethood. The IAU flung him down into dwarf-planet status. ‘Xena’
