Here's why:

* Stars are giant balls of hot gas that produce their own light and heat through nuclear fusion.

* Mercury, Venus, Earth, Mars, Jupiter, and Saturn are planets. They are celestial bodies that orbit a star and do not produce their own light. They reflect the light of the Sun.

* The Moon is a natural satellite that orbits Earth. It also doesn't produce its own light.

Let me know if you have any other questions!