Astronomers, hold on to your telescopes. The solar system has 12 planets, not nine.

That’s the earthshaking conclusion of an influential international committee, which today will recommend a new definition of what qualifies as a planet.

The move is necessary, experts say, because of discoveries in the past decade that have revealed a glut of Pluto-size bodies beyond the orbit of Pluto - until now considered the farthest planet from the sun.

Those findings sparked an intense debate among planet-watchers: Should the new worlds be welcomed as planets, or was it a mistake to call tiny Pluto a planet in the first place? Now there’s an answer that might satisfy Pluto-boosters and Pluto-phobes alike.

Pluto would remain a planet - and its largest moon plus two other heavenly bodies would join Earth’s neighborhood - under a draft resolution to be formally presented today to the International Astronomical Union, the arbiter of what is and isn’t a planet.

"Yes, Virginia, Pluto is a planet," quipped Richard Binzel, a professor of planetary science at the Massachusetts Institute of Technology.

The proposal could change, however: Binzel and the other nearly 2,500 astronomers from 75 nations meeting in Prague to hammer out a universal definition of a planet will hold two brainstorming sessions before they vote on the resolution next week. But the draft comes from the IAU’s executive committee, which only submits recommendations likely to get two-thirds approval from the group.

Besides reaffirming the status of puny Pluto - whose detractors insist it shouldn’t be a planet at all - the new lineup would include 2003 UB313, the farthest-known object in the solar system and nicknamed Xena; Pluto’s largest moon, Charon; and the asteroid Ceres, which was a planet in the 1800s before it was demoted.

The panel also proposed a new category of planets called "plutons," referring to Pluto-like objects that reside in the Kuiper Belt, a mysterious, disc-shaped zone beyond Neptune containing thousands of comets and planetary objects. Pluto itself and two of the potential newcomers - Charon and 2003 UB313 - would be plutons.

If the resolution is approved, the 12 planets in our solar system listed in order of their proximity to the sun would be Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto, Charon and the provisionally named 2003 UB313. Its discoverer, Michael Brown of the California Institute of Technology, nicknamed it Xena after the warrior princess of TV fame, but it likely would be rechristened something else later, the panel said.

The galactic shift would force publishers to update encyclopedias and school textbooks and elementary school teachers to rejigger the planet mobiles hanging in classrooms.

Even if the list of planets is officially lengthened when astronomers vote on Aug. 24, it’s not likely to stay that way for long: The IAU has a "watchlist" of at least a dozen other potential candidates that could become planets once more is known about their sizes and orbits.

"The solar system is a middle-aged star, and like all middle-aged things, its waistline is expanding," said Jack Horkheimer, director of the Miami Space Transit Planetarium in the United States and host of Public Broadcasting’s "Stargazer" television show.

Opponents of Pluto, which was named a planet in 1930, still might spoil for a fight. Earth’s moon is larger; so is 2003 UB313 (Xena), about 70 miles wider. Roundness is key, experts said, because it indicates an object has enough self-gravity to pull itself into a spherical shape. Yet Earth’s moon wouldn’t qualify because the two bodies’ common center of gravity lies below the surface of the Earth.

"People were probably wondering: If they take away Pluto, is Rhode Island next?" Binzel quipped. "There are as many opinions about Pluto as there are astronomers. But Pluto has gravity on its side. By the physics of our proposed definition, Pluto makes it by a long shot."