Trouble is, we already have plutons -- on Earth. For more than 100 years, geologists have used "pluton" to describe a common type of rock with molten origins that, unlike lava, remains underground and cools there.
Allen Glazner, a UNC-Chapel Hill geologist, studies plutons. Recently he helped revise long-held ideas about the speed with which they form, refining understanding of Earth's crust.
Glazner, 51, did not relish the idea of future students marching into UNC classrooms assuming plutons were a spaceship trip away when they are abundant underfoot.
So, when astronomers announced their plans last week, Glazner fired off a passionate e-mail defense of his field's ownership of the word. Copies went to leaders of the International Astronomical Union, which is meeting in Prague, Czech Republic.
"It's not like it's an obscure term," said Glazner. "It's in every dictionary I've looked at since."
Dozens of other geologists told him they wanted the stargazers to find another word, too.
Geology too often gets slighted by the rest of science, said John Geissman, a University of New Mexico geologist and a member of the Geological Society of America's governing council.
The field is a vital discipline, he said. But large numbers of students aren't required to study it as they must tackle chemistry or physics.
"Geologists need to do a better job of sticking their necks out and defending their science," Geissman said.
This week, Glazner's complaint started showing up in science-oriented news outlets, even in the national press. On Tuesday, Geissman's group crafted a protest message to the International Astronomical Union.
"The Geological Society of America urges the IAU to adopt a term for a new category of planet that does not conflict with one so commonly used by another scientific discipline," they wrote.
Before the day was over, victory appeared in the hands of the earthbound.
Ron Ekers, president of the International Astronomical Union, sent Glazner e-mail. His organization, he wrote, intended to find a replacement for plutons.
Glazner is pleased and relieved. He's hoping a new term can be selected by Thursday, when the astronomers are expected to vote on how best to recategorize the planets. "I'm not generally a rabble-rouser," the Chapel Hill professor said. "But I just wanted to let them know."