The planet plot thickens. Over the past few days, two rival definitions of the term 鈥減lanet鈥� have been put forward by astronomers gathered in Prague at a meeting of the International Astronomical Union.
The first definition would potentially give our solar system hundreds of planets. The second would require a planet to dominate its neighbourhood and would throw out all the distant iceballs beyond Neptune, including little Pluto, and leave only eight planets (see Pluto may yet lose planet status).
Since an international group of astronomers proposed it unexpectedly on Friday, the second proposal has received a lot of support. In fact, Caltech鈥檚 Mike Brown, who has discovered many objects that would be upgraded to planets under the first scheme, actually prefers the second.
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鈥淚 just read the new proposal and I liked it enough to ask them to sign my name to it, too,鈥� Brown told New Scientist. 鈥淚t鈥檚 really the only reasonable scientific definition around.鈥�
Broken down
Originally, it looked like the two proposals might go head-to-head in a vote on Thursday. But the IAU鈥檚 executive committee decided otherwise on Monday.
In an attempt to offer a compromise between the two options, the definition will instead be broken down into components drawn from both definitions. The vote鈥檚 actual wording will not be released until Tuesday, says Owen Gingerich of Harvard University in Massachusetts, US.
鈥淲e think we鈥檝e done something for both camps, so this has a chance of being less contentious,鈥� Gingerich, head of the group that devised the first definition, told New Scientist.
But the vote is still likely to be controversial, since it will decide whether Pluto is demoted.
