Here's why:

* Nuclear Fusion: The sun is a giant ball of hot gas, primarily hydrogen and helium. At its core, the immense pressure and temperature cause nuclear fusion to occur. This is a process where hydrogen atoms combine to form helium, releasing enormous amounts of energy in the form of light and heat.

* Electromagnetic Radiation: The energy released by fusion travels through space as electromagnetic radiation, which includes visible light, infrared radiation (heat), ultraviolet radiation, and other forms of radiation.

So, the sun doesn't just reflect light from other sources, it produces its own light through nuclear fusion.