Researchers are now pretty certain there's a ninth planet in the solar system.
Konstantin Batygin and Mike Brown, two CalTech scientists, say the new planet is about 10 times the mass of Earth and has an atmosphere of hydrogen and helium. Science magazine reports that the mysterious "Planet X" moves in a distant orbit beyond Neptune1.
The researchers haven't observed Planet X itself, but believe it exists because of the unique configuration2 of six objects when they come closest to the sun, according to Science.
The scientists say that there's a 0.007 percent probability that the configuration is due to chance, and instead are confident it's a ninth planet. They believe they will observe the planet with a telescope within five years, according to The Associated Press.
So where did this possible planet come from? Scientists have previously3 speculated that there could be a missing planet in our solar system, with some theorizing that a collision caused it to be ejected out of our system some 4 billion years ago. That collision may have been with Jupiter.
"Although we were initially4 quite skeptical5 that this planet could exist, as we continued to investigate its orbit and what it would mean for the outer solar system, we become increasingly convinced that it is out there," Batygin said in a statement. "There is solid evidence that the solar system's planetary census6 is incomplete."
Batygin and Brown described their findings in The Astronomical7 Journal on Wednesday.