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Turns out Pluto might really be a giant comet

Some researchers have a new theory about the former planet: It's made up of a billion comets at its core.

Eric Mack Contributing Editor
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Eric Mack
2 min read
NASA/JHUAPL/SwRI

Ever since poor Pluto was stripped of its planetary status, a lingering question has been, Well then, what the heck is it? Dwarf planet? Big asteroid? Just another Kuiper Belt Object? There's an argument to be made that it's all three, but new research suggests it may also be something a little more unique: a really overgrown comet. 

Scientists from the Southwest Research Institute (SwRI) combined data from NASA's New Horizons flyby of the former planet and the European Space Agency's Rosetta mission that landed on comet 67P to come up with a new explanation for how Pluto came to be.

9 crazy things we learned about Pluto in the past year

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"We've developed what we call 'the giant comet' cosmochemical model of Pluto formation," Dr. Christopher Glein of SwRI said in a release.

The researchers discovered that a large, nitrogen-rich ice glacier on Pluto's surface named Sputnik Planitia is similar in composition to what Rosetta found on its comet.

"We found an intriguing consistency between the estimated amount of nitrogen inside the glacier and the amount that would be expected if Pluto was formed by the agglomeration of roughly a billion comets or other Kuiper Belt objects," Glein explains.

The researchers also looked into another possible model in which Pluto formed from very cold ices. They say that while there are still many unanswered questions about what exactly Pluto is and how it came to be, the notion that it is basically a billion ancient comets at its core is a clear possibility.

The theory is laid out in a paper published online on Wednesday in the journal Icarus

The notion that Pluto is a giant comet probably won't satisfy those who still think it should be considered a planet, but look at it this way: If collecting comets is the currency of the cosmos, then Pluto is our solar system's biggest billionaire.

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