New Dwarf Planet Found At The Solar System's Outer Limits

Enlarge this image toggle caption Scott S. Sheppard/Carnegie Institution for Science Scott S. Sheppard/Carnegie Institution for Science

Scientists have spotted a new dwarf planet at the edge of our solar system. It's a kind of pink ice ball that's way out there, far beyond Pluto.

Astronomers used to think this region of space was a no man's land. But the new findings suggest that it holds many small worlds — and there are even hints of an unseen planet bigger than Earth.

"We used to think there's just not much out there. But it turns out there are some interesting things," says Chad Trujillo, an astronomer at the Gemini Observatory, a big telescope on a mountaintop in Chile.

Until now, the only object detected in that part of our solar system was a dwarf planet called Sedna, after an Inuit goddess said to live in the frigid Arctic Ocean. That discovery was made a decade ago, and since then scientists have wondered: Is Sedna alone?

"Because you never know, if you just find one thing, is it just some strange oddity, or is it actually the first of many more objects?" Trujillo says.

The trouble is, looking for them has been hard. These distant things don't emit their own light. Light from the sun has to travel billions of miles out there, reflect off the object and then come billions of miles back. Along the way, some light gets lost.

"As objects get farther and farther away, they get much fainter, and it's a big effect," Trujillo says.

Still, he's been trying to find other Sednas. And now he's got one.

He and Scott Sheppard, of the Carnegie Institution for Science in Washington, D.C., have spotted another dwarf planet that stays even farther out than Sedna.

This little world is about 280 miles across, and one orbit around the sun takes it about 4,000 years. "The object has a pinkish hue to it, so it would look a little pink, maybe a little reddish," Sheppard says.

If you were standing on this ball of ice, it would be cold — around minus 400 degrees Fahrenheit — and it would be dark. "The sun would just be basically another bright star in the night sky," Sheppard notes. "It wouldn't be much more than that."

Until the ice ball gets a permanent name, it's just called a bunch of letters and numbers that follow a standard format. So it's known as 2012 VP113. "For short we've just been calling it VP, or sometimes we even just call it Biden," Sheppard says. "Affectionately, we call it Biden, just because of the VP."

He thinks Biden and Sedna probably have company — thousands of objects that are bigger than this one that's just been found.

In fact, here's something more that Sheppard says was mind-blowing: Biden, Sedna and some other bodies at the edge of the Kuiper belt have a strange similarity in their orbits — one that suggests they're all being influenced by the presence of something big, perhaps an unseen planet that could be up to 10 times the size of Earth.

"So we just need to find more of these objects to see really what's happening," Sheppard says. "But it's definitely a probable thing that there could be a very large object out there."

The scientists describe their findings in the journal Nature, and other astronomers say it's exciting.

"It shows you that there are large regions of our solar system that we still know next to nothing about," says Mike Brown, an astronomer at Caltech who was part of the team that discovered Sedna. He's relieved that, as he hoped, it's not lonely.

And Brown loves the idea that there might be an even bigger planet out there. "It's a great idea. I hope it's actually true," he says. "It would just be awesome."

Figuring out what lies in this part of our solar system should provide clues to help astronomers understand how our solar system formed, says Meg Schwamb, an astronomer at Academia Sinica in Taipei, Taiwan.

She notes that when Pluto was discovered, it took many years to figure out that it was actually part of the band of icy bodies known as the Kuiper belt. Now astronomers are going through that same process for this region beyond the Kuiper belt, and new technologies should soon make it easier to search for these distant objects.

"We knew there was one. Now there are two," Schwamb says. "We're going to find more."