How Does Evidence of a Ninth Planet Work?

There’s a giant planet hiding way out in our solar system that scientists think might be there because of how other planets and space rocks move.

Imagine you're playing with marbles on a table, and all the marbles are moving around in a pattern. Then one day, you notice some marbles are swerving or changing direction, not because they’re being bumped by something you can see, but because there’s another marble somewhere far away that's pushing them gently from behind. That hidden marble is like the ninth planet.

Scientists look at how space rocks, called dwarf planets, move and where they are in the sky. If a lot of them seem to be grouped together or moving in similar ways, it might mean something big, like another planet, is influencing them from far away.

They use math and computers to imagine what could cause those movements. It's like solving a puzzle with numbers. If their guess matches what they see in the sky, that’s strong evidence there might be a hidden planet out there, waiting to be found!