When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works. The speed of light traveling through a vacuum is exactly 299,792,458 meters (983,571,056 feet) ...

On one hand, the speed of light is just a number: 299,792,458 meters per second. And on the other, it’s one of the most important constants that appears in nature and defines the relationship of ...

James is a published author with multiple pop-history and science books to his name. He specializes in history, space, strange science, and anything out of the ordinary.View full profile James is a ...

In 1676, by studying the motion of Jupiter's moon Io, Danish astronomer Ole Rømer calculated that light travels at a finite speed. Two years later, building on data gathered by Rømer, Dutch ...

Imagine you’re in a car driving across the country watching the landscape. A tree in the distance gets closer to your car, passes right by you, then moves off again in the distance behind you. Of ...

Imagine a tiny needle traveling toward Earth at the speed of light. At first glance, it might seem harmless, since it is so small. However, at such extreme speeds, even a microscopic object could ...

Imagine you’re in a car driving across the country watching the landscape. A tree in the distance gets closer to your car, passes right by you, then moves off again in the distance behind you. Of ...

If the speed of light were much slower, a lot of very odd effects, from redshift to time dilation, would be a lot more ...

The universe has a speed limit, and it's the speed of light. Nothing can travel faster than light — not even our best spacecraft — according to the laws of physics. So, what is the speed of light?