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Discovery of possible dwarf planet could lead astronomers to Planet Nine

Nov 18, 2016

 


We're learning a lot about our tiny corner of the cosmos these days. That's thanks to improving technology and the increasing number of probes we're sending into the solar system.

But as much as we learned so far, there’s still a lot about space that we don't know.

Recently, researchers have been trying to track down a theoretical Planet Nine. (That's the title formerly held by Pluto. Sorry, Pluto.)

University of Michigan astronomers recently came across a planetary surprise that might get us closer to that discovery. And it turns out Pluto might have a friend out there after all.

Astronomy professor David Gerdes sat down with us today to talk about an object that caught his team’s eye in the distant reaches of the solar system.

“We’ve found what we think is a dwarf planet, a small minor planet that’s orbiting in the solar system beyond Neptune, far, far, far beyond Pluto,” Gerdes said.

The object was given the designation 2014 UZ224 by the Minor Planet Center. An official name can be proposed after its orbit has been observed and refined for several more years, but for now the team is calling it “DeeDee." That's short for “distant dwarf.”

Gerdes told us DeeDee is more than twice as far away from Earth and the sun as Pluto. That puts it somewhere in the ballpark of 8.5 billion miles from the sun.

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The team estimates DeeDee is a little over 320 miles in diameter, which is “right at the border line for dwarf planethood.”

According to Gerdes, there’s no doubt DeeDee exists, but it’s less certain whether or not it’s truly a dwarf planet.

"What I like about what we've done is we've found a way to use this data set for something other than what it was originally intended to do."

“This was found with a ground-based telescope, not with a space probe,” he said.

This wasn't your garden variety hobby spyglass, though. The telescope is four meters in diameter.

Gerdes’ team didn’t set out to find any new planets. They were looking to map distant galaxies in order to understand more about the large scale structure and expansion of the universe.

“Although our goal is to look at distant galaxies, we’re looking out through the dusty window of our solar system and there’s stuff in the foreground that gets in the way,” he said.

Gerdes told us that DeeDee is cool not because it’s special or unique, but because it might not be.

“To me the interesting thing about it is that [dwarf planets like DeeDee] are probably fairly common. There are probably many more of them, and there may be an even bigger prize out there,” he said.

"DeeDee is cool, I'm happy we found it ... but to me it is pointing the way to larger discoveries out there like Planet Nine."

The thought is that the techniques and technology Gerdes and his team developed to pick out these incredibly faint, mind-bogglingly distant objects could help in the search for a ninth planet.

“Planet Nine was motivated by the idea that if you look at the trans-Neptunian objects with the very longest periods, even longer than DeeDee, objects that take thousands of years to go around the sun, they follow along elliptical orbits like DeeDee too," Gerdes said. "But there’s a special thing about those orbits. The ellipses line up in the same direction. They’re long, skinny things that all point one way, as though they are under the influence of a yet even more distant massive object that’s pulling those objects to one side. The shorter-period objects don’t do that, they’re random. But if you look at the longest-period ones, they seem to be under the influence of something else.”

Gerdes told us that Planet Nine’s orbit has been worked out, but it’s unknown where along its orbit the planet might currently be.

“What we know is a band on the sky where Planet Nine might be,” he said. A portion of that band intersects with the part of the sky that Gerdes’ survey is looking at.

“If Planet Nine happens to be in there, I believe it is bright enough to show up in our data, and in the next year or so we’ll know if it’s there or not,” he said. “It’s a matter of months to a year, not decades.”

In our conversation above, Gerdes talks more about Planet Nine and how his team discovered DeeDee.