Data From New Horizons Brings Pluto’s Planet Classification Back Into Question

The scientific community loves a good debate, and perhaps one of the most on-again, off-again debates is about Pluto — is it a planet? On Friday, NASA’s planetary scientists jumped back in the debate after revealing that the dwarf planet is geologically active.

New Horizons Pals up with Pluto

In a press conference on Friday, new data from New Horizons indicated that Pluto is, in fact, quite a bit more complex than scientists originally believed.

“It’s very hard not to call an object with this level of complexity in its geology, and such complex seasons, a planet,” said Alan Stern, New Horizons principal investigator at Southwest Research Institute.

According to the press conference, Pluto has an extensive, hazy atmosphere, and new glacier plains made up of nitrogen ice that are still actively carving away at Pluto’s surface. Scientists originally believed that Pluto was struck by an object so large that it blew bits of its mass away, which created its five moons. Oddly enough, there is no evidence of this impact since the dwarf planet’s surface is clean and almost perfectly spherical.

Making a Case Against Pluto

Back in 2006 the International Astronomical Union (IAU) delisted Pluto as a planet, ‘downgrading’ it to a dwarf planet. However, the original vote was so close that the new information being brought to light by New Horizons might force the IAU to reconsider.

In the original debate, the IAU had defined a planet as having three defining characteristics: it has to orbit around the sun, it must have a spherical shape, and it has to have “cleared the neighborhood” around its orbital plane.

Pluto has always been a little different from the rest of the gang, though. It’s smaller than our own moon, for instance, and it has an incredible elliptical orbit around the Sun, which is unique when compared to all of the other planets.

Unfortunately, it’s the third defining characteristic that puts a heavy damper on letting Pluto join the club again. The dwarf planet is located just in the inner edge of the Kuiper Belt, which is a collection of icy bodies right at the edge of the solar system. The more bodies discovered in the Kuiper Belt, the more the odds stack against the dwarf planet.

NASA Goes to Bat for Pluto

Stern has been poking holes in the IAU’s definition of a planet since 2006, so it’s no surprise that he’s using this new information to further cement his stance on Pluto’s planetship.

As Stern points out, most planets in the Solar System don’t have stable orbits, there are still plenty of asteroids cruising around Earth, Mars, and Jupiter. Last of all, Stern notes that less than five percent of the entire astronomical community voted to delist Pluto.

Despite Stern’s obvious bias, Pluto is getting plenty of support elsewhere, too. New Mexico and Illinois have both passed legislation which defines Pluto as a planet. There is also a lot of public support from people who just want to see the old band get back together.

Unfortunately for Pluto, its fate is tied to New Horizons. As it continues its mission to explore other bodies located in the Kuiper Belt, scientists will have a better understanding of Pluto’s neighbors and decide on a final classification.


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