The most common natural object that emits its own light is the Sun.

Here's why:

* Nuclear Fusion: The Sun generates light and heat through nuclear fusion, a process where hydrogen atoms combine to form helium, releasing tremendous amounts of energy in the form of light and heat.

While the Sun is the most obvious example, there are other natural objects that emit light:

* Stars: Like the Sun, stars are massive balls of hot gas that produce light and heat through nuclear fusion.

* Lightning: This electrical discharge in the atmosphere generates a bright flash of light.

* Fireflies: These insects have specialized organs that produce a chemical reaction that creates light.

* Bioluminescent organisms: Certain marine creatures, like jellyfish and some fish, produce light through chemical reactions within their bodies.

These are just a few examples, and there are many other natural objects that emit light in various ways.