The solar system might have nine planets after all.
Nearly a decade after Pluto was demoted to dwarf status, researchers at the California Institute of Technology announced Wednesday they think there is a planet 10 times larger than Earth orbiting along the edges of our celestial neighborhood, and they plan to use a telescope on Mauna Kea to prove its existence.
If they’re correct, it would be the first true planet discovered in our solar system since Neptune was observed in 1846.
“It’s like discovering a new continent or something,” said Mike Brown, a Caltech astronomer who co-authored the report with colleague Konstantin Batygin. “It’s really big.”
The researchers say the presence of a planet 20 times farther from the sun than Neptune would explain the odd orbits of several objects in the Kuiper Belt. Based on its estimated size, the planet, if it exists, likely would be a gas body that was nearly ejected entirely from the solar system in its early days.
Its incredible distance from the sun means it would take 10,000 to 20,000 years to complete an orbit.
This isn’t the first time the existence of such a planet has been proposed, but Brown, whose research led to Pluto’s downgrade in 2006, says they have the data to back up their claim.
“We spent two years on this,” he said. “A lot of that two years was trying to prove that we were wrong because it sounds ridiculous.”
The proof will come in actually observing the planet, and Brown doesn’t plan to waste any time.
He said he will use his research time at Mauna Kea’s Subaru telescope in March to scan the solar system’s outer reaches for what would be a long lost cousin of our own planet.
“This is the start of the hunt as opposed to the discovery,” Brown said.
Of all the telescopes in the world, astronomers say Subaru has the best chance of finding it thanks to its wide-field Hyper Suprime-Cam.
Still, the chances of spotting it right away are small even if he knows generally where to look.
“It’s no longer a needle in a haystack,” Brown said, adding it could take five years to discover. “It’s more like a needle in a hay bale.”
It’s also a search he won’t be doing alone.
Chad Trujillo, a Gemini astronomer whose 2014 paper provided the first clues of the planet’s existence, said he also will be using the Subaru telescope to take part in the hunt.
“It’s kind of like a friendly competition,” he said.
Trujillo, a University of Hawaii graduate who worked with Brown as a postdoctoral scholar, said he began thinking there might be something large in the outer solar system after discovering an object known as VP113. He said its orbit, which involved clumping with other objects, was hard to explain, but he and co-author Scott Sheppard didn’t take it any further at the time.
“I would say we had the idea, but Mike and Konstantin did a lot more work,” Trujillo said.
At first, Trujillo said he also was hesitant to even suggest that a large unknown planet might be out there.
“I think at the time we kind of expected everyone to say we were crazy or something,” he said. “And we kind of expected people might give us reasons why we are wrong. We are actually kind of surprised people seemed to support the idea.”
If it’s found, the planet would explain one of the peculiarities of the solar system.
“Our solar system is unique,” Brown said. “It doesn’t have the most common type of planet in the galaxy, which is something in between Earth and Neptune, and now it looks like it does.”
Email Tom Callis at tcallis@hawaiitribune-herald.com.
