Updating a story I posted last week, astronomers meeting in the Czech Republic have decided that Pluto no longer meets the qualifications of a full-fledged planet. The astronomers gathered voted to demote Pluto to the status of dwarf planet, a new category which also includes the asteroid Ceres and UB313 (aka “Xena”). Pluto got the boot because it doesn’t have enough mass to maintain a spherical orbit around the sun — its orbit interferes with that of Neptune.
Now only the eight classical planets will be considered true planets. Third-grade science teachers everywhere are reported desperately thinking up new mnemonic devices before the school year starts.