At its heart, Pluto may be a gigantic comet.
Researchers have come up with a new theory about the dwarf planet's origins after taking a close look at Sputnik Planitia, the vast nitrogen-ice glacier that constitutes the left lobe of Pluto's famous "heart" feature.
"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 similar in chemical composition to 67P, the comet explored by Rosetta," Chris Glein, a scientist at the Southwest Research Institute (SwRI) in San Antonio, said in a statement. [Photos of Pluto and Its Moons]
The European Space Agency's Rosetta mission orbited Comet 67P/Churyumov-Gerasimenko from 2014 through 2016.
The orbiting mothership also dropped a lander named Philae onto the icy body, pulling off the first-ever soft touchdown on a comet's surface. (The Kuiper Belt is the ring of frigid objects beyond Neptune's orbit; Pluto is the belt's largest resident.)
Glein and his SwRI colleague Hunter Waite devised the new Pluto-formation scenario after analyzing data from Rosetta and NASA's New Horizons mission, which flew by Pluto in July 2015.
The scientists also made some inferences about the dwarf planet's evolution in their new study, which was published online May 23 in the journal Icarus.
"Our research suggests that Pluto's initial chemical makeup, inherited from cometary building blocks, was chemically modified by liquid water, perhaps even in a subsurface ocean," Glein said.