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Researchers Say There’s a 40 Percent Chance of a Ninth Planet in the Solar System – and It Sounds as Wild as It Is

New planet?

Mikkel Preisler
By Mikkel Preisler 23. June 2025

As if our own solar system didn’t already have enough going on with solar storms, dark energy, and retrograde Mercuries, researchers are now throwing another cosmic bomb onto the table: There’s up to a 40% chance that we actually have a hidden ninth planet out there somewhere. Yep – Planet Nine, or Planet X, as some call it. And no, it’s not a joke.

Hidden in Pluto’s Shadow – Maybe

If Planet Nine exists, it’s hiding way out in the cold dark. We’re talking 100 times further away from the Sun than Earth. Between 5 and 10 times heavier than Earth. And roughly 65 billion kilometers out in the unknown. Out there, where the Sun no longer warms, and temperatures drop to -245 degrees Celsius. A frozen giant – an invisible colossus that may have been hiding from our telescopes all along.

It’s researchers from Rice University in Texas who have reignited the theory. Using simulations and models of how planets behave in “chaos mode” in young solar systems, they believe there’s a good chance that Planet Nine was never completely ejected but instead got caught in an ultra-wide orbit around the Sun.

An Interstellar Pinball Machine

“It’s like watching planets play pinball with each other,” says research leader André Izidoro. “Large planets can knock each other off course, but in some cases, they get caught in outer orbits instead of being sent out into interstellar darkness.”

It’s a theory that has been circulating for nine years – and that has divided astronomers and space enthusiasts into two camps. Either it exists, or it’s the biggest cosmic dead end since Pluto was downgraded to a dwarf.

Can We Find It?

Maybe. Because later this year, the new Vera C. Rubin Observatory in Chile will switch on the world’s most powerful camera. And it will be set to search the sky for just such hidden giants. If Planet Nine exists – and it’s not an expert in intergalactic hide and seek – this might be the year we finally capture it on camera.

If It Exists, It Changes Everything

It’s not just about one extra planet in the outer reaches. It’s about our entire understanding of how solar systems form. It opens up the possibility that our little family of planets isn’t so special – and that giant planets hiding in the darkness may be the rule, not the exception.

So next time you gaze up at the stars and feel small and insignificant – remember: There may be a whole planet out there still waiting to be discovered. And it could change the entire game.

Our team may have used AI to assist in the creation of this content, which has been reviewed by our editors.

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