Say it like this

An enormous ball of burning gas, so far away it looks like a dot. Our sun is one.

For the grown-up

A star is a mass of gas held together by gravity, generating energy by nuclear fusion in its core. The sun being an ordinary example of one is usually the most surprising fact in the topic for a young child.

The easy mistake

Careful here. Starlight is old. Some of what you are looking at left before anybody alive today was born, which makes the night sky a picture of the past rather than the present.

Words next to this one

Galaxy An enormous group of stars travelling together. Ours has a couple of hundred billion in it. Universe Everything there is, including you. Most of it is empty space. Gravity The pull that everything with weight has on everything else. Bigger things pull harder. Orbit Going round and round something because it keeps pulling you in and you keep missing it.