It could be something even cooler.
And it could help prove the existence of Planet Nine.
It could be the largest moon we've ever seen
Step one: realize we're not alone.
Is there a planet—or even planets—waiting to be discovered out there?
Something's got the Kuiper belt's rocks off, and there's a scramble to find it.
It's time to return to our hellish neighbor.
We think you can, Opportunity.
Another day, another hypothetical object on the outskirts of the solar system.
So hot right now.
Scientists aren't just jerking you around—this is about something more than your childhood nostalgia
New evidence suggests it could be a rogue planet captured by our sun
Finally, a good use for climate change
Now to figure out if it has liquid water. Or an atmosphere.
Giant planet orbits three stars at once
Where can I find a planet like that?
How skeptical should we be, and how will we find out if this mystery planet is really out there?
Scientists are hot on the trail of our solar system's 9th planet
Short answer: It depends who you ask
And he thinks the upcoming flyby will prove it
This year's missions to the outer solar system are set to shake up the planetary family tree
The Dawn spacecraft arrives at Ceres this March, and it could be the most surprising space mission in decades
Happy Carl Sagan day! Celebrate with this blast from the past in the pages of Popular Science