Pluto Learns Eight Is Enough for Planets

Like the Edsel, the Flying Wing, and the Austro-Hungarian Empire, the ninth planet became a relic of history Thursday when international astronomers meeting in the Czech Republic decided Pluto was too small to remain a full member of the planetary club.

Members of the International Astronomical Union overwhelmingly voted to demote Pluto to a "dwarf planet." Though still retaining the term planet, it was clear that Pluto had been exiled.

"Pluto's out," said Michael E. Brown, the Caltech astronomer whose discovery last year of a planet-like object called UB313 reignited the long-running debate over whether Pluto should be considered a planet. "People are going to be unhappy, but it's the right thing to do. This is a great moment in science."

"I'm just glad they decided something," said Marc Buie, an astronomer at the Lowell Observatory in Flagstaff, Ariz., where Pluto was discovered in 1930.

The vote reverses a recommendation made last week by a committee of the IAU, the sole authority for classifying and naming astronomical bodies.

The earlier proposal said that to be a planet, a body need only be round and orbit the sun.

Under that definition, there would have been dozens of new planets added to the solar system, something the astronomers gathered in Prague refused to accept.

Instead, the astronomers adopted a definition that also requires a planet to "clear its area," meaning that it dominates in its neighborhood of the solar system and prevents any other similar-sized objects from forming. That eliminated Pluto, one of thousands of objects in the Kuiper Belt, 3.6 billion miles from the sun.

"Poor little Pluto," said Patricia Tombaugh, the 93-year-old widow of the man who discovered Pluto, Clyde Tombaugh. "Kids are going to be upset."

Tombaugh, who lives in Las Cruces, N.M., said children love Pluto because "it's little like they are."

Children interviewed at the California Science Center in Exposition Park were disappointed. "It's an awesome planet," said Jaykb Olivas, 6. "Since Pluto's the smallest planet, we could visit it and be like a giant."

Some parents who had grown up memorizing the names of the planets, using mnemonics like "My Very Excellent Mother Just Served Us Nine Pizzas," seemed more distressed.

"I feel like something's missing," said Micaela Chambers, 39, of Granada Hills as she played with her son outside the science center.