A planet is a big round object in space that goes around a star, like our sun. Imagine a ball rolling in a big circle! Planets are made of rock and gas, and some can be very hot or very cold.
There are many planets in our solar system, which is the group of planets that go around the sun. One of them is Earth, where we live! Earth is a special planet because it has everything we need to grow, like water and air.
Next time you look up at the night sky, try to imagine these big balls far away in space!