Stars are gigantic balls of gas, mostly hydrogen gas. There is so much gas and other material that the gravity of this huge gas-ball holds everything together. There is so much gravity that the gas becomes very dense and hot.

What we see of stars is the energy released from the nuclear reactions inside their cores and then radiated from the surface. Since most stars are VERY far away, the light takes anywhere from a few years to millions of years to reach us. So the star light that we see is very old indeed.

Stars come in a variety of sizes and brightness. Larger stars usually shine more brightly than smaller stars do. So, how bright a star appears in the night sky depends on its size as well as how far away from us it is. The closest star is about 39,900,000,000,000 kilometres away, while the farthest stars are billions of times farther than that.

What are satellites

A satellite is basically any object that revolves around a planet in a circular or elliptical path. The moon is Earth's original, natural satellite, and there are many manmade satellites, usually closer to Earth. A satellite launch can cost anywhere between $50 million and $400 million.