In a stunning reversal of fortune, it now seems likely that Pluto will lose its title of planet. Astronomers have been debating for years whether Pluto should count as a planet.
On the one hand, the say, it always has. On the other hand, it's much smaller than Earth, smaller even than Earth's moon.
Scientists meeting in Prague with the International Astronomical Union were presented with a new definition of the word "planet" last week. That definition would have included Pluto as a planet. But the proposal met with fierce protests. Opponents argued that there are hundreds of objects like Pluto out beyond Neptune.
Critics say they will back a definition that would consider designating a sort of dwarf object -- but not a planet.