Pluto no longer a planet, astronomers say

Here's my latest article, on National Geographic News

Pluto has been voted off the island

The distant icy ball is no longer a true planet, according to a new definition of the term voted on by scientists today.

"Whoa! Pluto's dead," said astronomer Mike Brown, of the California Institute of Technology in Pasadena, as he watched a Web cast of the vote. "There are finally, officially, eight planets in the solar system."

In a move sure to generate controversy even as it forces textbooks to be rewritten, Pluto will now be dubbed a "dwarf planet."
But it's no longer part of an exclusive club, since there would be more than 40 of these dwarfs, including the large asteroid Ceres and 2003 UB313, nicknamed Xena—a distant object slightly larger than Pluto discovered by Brown last year.

Researchers voted on the definition at a meeting of the International Astronomical Union in Prague, in the Czech Republic. This group decides on the official names of all celestial bodies....

Read more and check back later—we'll be posting a longer version later today.