Thermoremanent magnetization

Okay kiddo, have you ever played with magnets? They can attract certain things and stick together, right?

Well, imagine if we had a bunch of tiny magnets inside of a rock. These tiny magnets are all pointing in different directions, so they cancel each other out and the rock itself doesn't act like a magnet.

But, if we heat up the rock and then cool it back down, the tiny magnets inside will begin to line up in the same direction. This is called thermoremanent magnetization.

So, now the rock will act like a magnet and have a north and south pole. We can measure this magnetization and use it to learn more about the history of the rock - like if it was once near a magnetic field or if it's been heated up before. Isn't science cool?!