Here's why:

* Stars are giant balls of hot gas. They are primarily composed of hydrogen and helium, and their immense gravity causes nuclear fusion reactions within their cores.

* Nuclear fusion releases energy in the form of light and heat. This is the same process that powers our Sun.

* The light from stars travels through space and reaches our eyes. We then perceive this light as twinkling points in the night sky.

While some objects in space, like planets and moons, reflect light from the Sun, stars themselves are the source of their own light.