The planet may also be linked to periodic mass extinctions on Earth.
Back in January, Konstantin Batygin and Mike Brown at the California Institute of Technology, discovered evidence hinting at the existence of Planet Nine — a massive planet at the edge of solar system that hasn’t yet been spotted by astronomers.
After studying six objects in the Kuiper Belt — a region of large icy bodies that circle the sun beyond Neptune’s orbit — they noticed that these Distant Kuiper Belt Objects (KBOs), have an unusual slingshot orbit. They shoot out to some of the most distant reaches of the solar system before swooping back in. However, what is odd about the orbits is that they all point in roughly the same direction, when they should be oriented randomly in space.
It is this alignment that prompted the researchers to suggest that an unseen planet, ten times as massive as Earth and four times its size, is guiding their path.
Daniel Whitmire, a retired astrophysics professor, wrote a paper stating that the mysterious planet may be linked with periodic extinctions on Earth. The paper links the periodic extinction events that happened on Earth — which can be seen in the fossil record — with the hidden Planet Nine.
Extinction events seem to happen once every 27 million years or so, and this has perplexed scientists for years. No one is really sure why comets tend to arrive on such a regular schedule. However, potential explanations have included a companion star to our sun or extra risk as we travel through the spiral arms of the Milky Way.
But the new hypothesis suggests that if the idea of the periodic extinctions are true, then the orbit of Planet Nine may be to blame. It proposes that as the planet moves around the solar system, it passes through the Kuiper Belt every 27 million years, knocking comets towards us and into the inner solar system.
Although the idea of Planet Nine has been around for years, Batygin and Brown were to the first to find convincing evidence the mysterious planet’s existence. And now they have more.
Even though what’s causing the particular orbits of the six objects in the Kuiper Belt has not been officially discovered, Batygin and Brown argue that the chance that this was a random occurrence is as low as 0.007 per cent. Although those are pretty good odds, the two suspect that the number could be much lower if there were more objects in the Kuiper Belt with similar alignments.
And last week, the researchers found one. The object was spotted in an outer solar system survey and announced in a talk given at the SETI Institute by Michele Bannister of the University of Victoria, Canada. The object is so new that it doesn’t have an official catalogue name yet, but according to the researchers, it’s easy to see that its orbit is exactly like the others.
“It’s smack-exactly where we predicted it should be,” said Brown to New Scientist (NS).
Hey Planet Nine fans, a new eccentric KBO was discovered. And it is exactly where Planet Nine says it should be. pic.twitter.com/oZn0RDq8JF
— Mike Brown (@plutokiller) March 24, 2016
The discovery was a huge relief for the researchers, who were worried they were seeing patterns that weren’t really there. “At least in my mind, it removes all doubts that the pattern that we’re seeing is real,” Brown told NS.
Although the pair has yet to run in-depth statistics on this latest object, Brown argues that it is likely to reduce the odds of the alignment occurring by random chance to about 0.001 per cent.
However, Greg Laughlin at the Lick Observatory in California is not yet convinced. “In addition to being clustered in their angle, they also should be pointing the same direction in three-dimensional space,” he explained to NS. However, it is currently not possible to tell.
But, if the object has that orbital inclination, which Laughlin and Brown expect it will, then “that makes it more likely that there’s some kind of dynamical explanation,” Laughlin said to NS. “And among the dynamical explanations that have been offered, the Planet Nine hypothesis seems to make the most sense.”
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