PRAGUE: Our solar system would have 12 planets instead of nine under a proposed "Big Bang" expansion by leading astronomers, changing what billions of schoolchildren are taught about their corner of the cosmos.
Much-maligned Pluto would remain a planet and its largest moon plus two other heavenly bodies would join Earth's neighbourhood under a draft resolution formally presented on Wednesday to the International Astronomical Union, the arbiter of what is and is not a planet.
"Yes, 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 IAU's executive panel, which only submits recommendations likely to get two-thirds approval from the group.
Besides reaffirming the status of puny Pluto whose detractors insist it should not be a planet at all the new lineup would include 2003 UB313, the farthest-known object in the solar system; Pluto's largest moon, Charon; and the asteroid Ceres, which was a planet in 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 potential newcomers Charon and 2003 UB313 would be plutons.
The provisionally named 2003 UB313's 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.
Opponents of Pluto, which was named a planet in 1930, still might spoil for a fight
Astronomers also were being asked to get rid of the term "minor planets", which long has been used to collectively describe asteroids, comets and other non-planetary objects. Instead, those would become collectively known as "small solar system bodies".
The galactic shift would force publishers to update encyclopaedias and school textbooks, and elementary school teachers to rejig the planet mobiles hanging from classroom ceilings.
Far outside the realm of science, astrologers accustomed to making predictions based on the classic nine might have to tweak their formulae.
Even if the list of planets is officially lengthened when astronomers vote on August 24, it is 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.