What can we learn from light?

By Teagan Wall

When you look up at the night sky and see stars, what you're seeing is light produced by those stars many years ago. Because this is how we study the stars, it helps to know a few cool things about light.

For example, light always travels at a constant speed, called the speed of light. It doesn't matter if the star giving off light is moving toward us, or away from us. This is different than most things.

Think of riding a skateboard while throwing a baseball. If the skateboard is moving toward the target when you throw the ball, the speed of the skateboard and the speed of the t...