Comets do not give off their own light. They reflect sunlight.

Here's why:

* Composition: Comets are primarily composed of ice, dust, and gas.

* Sunlight Interaction: When a comet gets close to the Sun, the ice starts to vaporize, creating a glowing cloud of gas and dust around the comet's nucleus. This cloud, called the coma, reflects sunlight, making the comet appear bright.

* Tail Formation: The solar wind pushes the gas and dust away from the comet, forming a long tail that also reflects sunlight.

So, while comets appear to be glowing, they are actually reflecting sunlight, not producing their own light.