In the darkness, a pinpoint of light becomes visible. Someone has turned on a flashlight. The pin­point grows to the size of the bulb. Because this is slow motion, only the bulb is bright. Nothing else lights up—yet.

Now the light begins to spread outward from the bulb. It fills a bigger and bigger space. As the light moves forward, it strikes little fog droplets, the ground, a sneaker, a tree, a cat. After each collision, some light bounces off. It is redirected. Some of it reaches a person's eyes. Only then can the light trigger the person's eyes and brain. In slow, stretched-out speech, the person says, "L000000-000000k! c-aaat!"

—A Black Hole Is NOT a Hole,
Carolyn Cinami DeCristofano

Why did the author include this description?

to explain how a star produces light
to explain how light travels
to explain how cats see in the dark
to explain how fog forms