Jacobi ellipsoid

Alright kiddo, so imagine you have a ball that is slightly squished at the top and bottom, but still round in the middle. That's kind of what a Jacobi ellipsoid looks like, except it's not a ball, it's actually a shape that scientists use to describe how planets and moons spin.

To understand why they call it an ellipsoid, think of an oval. If you squished the oval a little bit, it would look like an ellipse. An ellipsoid is just a three-dimensional version of an ellipse. It's like a stretched-out ball that's not perfectly round.

So what does this have to do with planets and moons spinning? Well, when something spins, it bulges out at the equator (the middle) and flattens at the poles (the top and bottom). Just like how the Earth is flatter at the poles than at the equator.

Scientists use Jacobi ellipsoids to describe how much a planet or moon bulges out when it spins. By knowing the size and shape of the Jacobi ellipsoid, they can learn a lot about the planet's or moon's interior, like whether it has a solid or liquid core.

So that's what Jacobi ellipsoids are all about. It's a fancy way for scientists to describe how planets and moons spin and what's inside of them.