Left: Pluto and and moon Charon
(Prague, Czech Republic) Earth's leading astronomers today approved a new definition of a planet, thus downgrading Pluto's status to that of a dwarf planet.
The International Astronomical Union (IAU) approved new guidelines that downsize the solar system from nine planets to eight. Pluto had held planetary status since its discovery in 1930.
Jocelyn Bell Burnell, a specialist in neutron stars who oversaw the proceedings, urged those who might be "quite disappointed" to look on the bright side.
"It could be argued that we are creating an umbrella called 'planet' under which the dwarf planets exist," she said, drawing laughter by waving a stuffed version of the Walt Disney character Pluto beneath an umbrella.
The gathered astronomers had been trying to differentiate between the eight classical planets - Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune - and Pluto, which is smaller than the Moon and has an orbit that intersects that of Neptune.
Pluto and its satellite Charon have been characterized by some astronomers as a binary planet, because they are closer in size than any other planet/moon combination in the solar system.