Light-second

A light-second is a measure of distance that tells you how far light can travel in one second.

Do you know how fast light travels? It travels very, very, very fast - so fast that it can travel all the way around the Earth seven times in just one second! That's really, really fast, isn't it?

Now, imagine you are standing on Earth and you want to know how far away something is in space. You can measure that distance using a special unit called a light-second.

For example, if you see a star that is one light-second away from Earth, it means that the light you're seeing right now from that star actually took one second to travel all the way from the star to your eyes.

So, a light-second is a way to measure very long distances in space, and it tells us how much time light needs to travel from one place to another. Cool, right?