Hill sphere

Hi kiddo, have you ever played with a ball and noticed how if you throw it very hard, it bounces and comes back to you, but if you don't throw it hard enough, it flies away? Well, planets in space have their own "throwing power", too!

Imagine a planet like Earth, it has gravity that pulls everything closer to it. But the truth is that this gravity doesn't stop at the Earth's surface. Instead, it extends far away from the planet's surface, creating something called the "Hill Sphere".

The Hill Sphere is like a bubble around the planet that shows how far its gravitational pull can reach. So, any object that comes inside this bubble will be attracted towards the planet while anything outside it will not be pulled towards the planet and instead will follow its own path.

Now imagine more planets in space, for example, Jupiter and Saturn. Their Hill Spheres would be larger than Earth's because they are bigger and have a stronger gravitational pull. This is why they have more moons orbiting around them than Earth does.

I hope you have understood what the Hill Sphere is now, and why it's important in space exploration!