Scientists discover a secret planet hidden in our solar system

There are eight planets in our solar system, plus poor old Pluto, which was demoted in 2006, but what if there were more?

Turns out that might be the case. Astronomers have calculated that there is a 7 percent chance that Earth has another neighbor hidden in the Oort cloud, a spherical region of chunks of ice and rock that is tens of thousands of times farther from the Sun than we are.

“It is entirely plausible that our solar system has captured an Oort cloud planet,” said Nathan Kaib, co-author of the work and an astronomer at the Planetary Science Institute.

Hidden worlds like this are “a class of planets that should definitely exist but have received relatively little attention” until now, he said.

If a planet is hiding in the Oort cloud, it is almost certainly an ice giant.

Large planets like Jupiter and Saturn are usually born as twins. However, they have enormous gravitational forces of their own and sometimes destabilize each other.

That could have led to a planet being expelled from the solar system entirely, or exiled to its outer reaches, where the Oort cloud resides.

“The surviving planets have eccentric orbits, which are like scars from their violent pasts,” said lead author Sean Raymond, a researcher at the Astrophysics Laboratory at the University of Bordeaux.

That means the Oort cloud planet could have a significantly elongated orbit, unlike the nearly perfect circle that Earth follows around the sun.

The problem is that when things are that far away, they are quite difficult to detect. “It would be extremely difficult to detect,” Raymond added.

“If a Neptune-sized planet existed in our own Oort cloud, there’s a good chance we wouldn’t have found it yet,” said Malena Rice, an MIT astronomer not involved in this work.

“Surprisingly, it can sometimes be easier to detect planets hundreds of light years away than those right in our own backyard.”

It’s time to get out the telescope.

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