[cosmos] pluto no longer a planet - official

Pluto was stripped of its status as a planet in Prague on Thursday, when astronomers from around the world redefined it as a "dwarf planet," leaving just eight classical planets in the solar system. Pluto is no stranger to controversy. In fact, it's been dogged by disputes ever since its discovery in 1930.

Many astronomers contend the ninth rock from the sun never deserved to be a full planet in the first place.

Discovered by Clyde Tombaugh of Arizona's Lowell Observatory, Pluto was classified as a planet because scientists initially believed it was the same size as Earth. It was the only known object in the Kuiper Belt and in 1978, it was found to have a moon - Charon. But in the 1990s, more powerful telescopes revealed numerous bodies similar to Pluto in the neighborhood.

Scientists agree that to be called a planet, a celestial body must be in orbit around a star while not itself being a star. It also must be large enough in mass for its own gravity to pull it into a nearly spherical shape and have cleared the neighborhood around its orbit.

Pluto's reaction to its downgrading has not been recorded.