Light-year

Okay kiddo, have you ever heard of a year? It's how long it takes for the Earth to go around the sun once. But did you know that there is also something called a light-year? A light-year is a way to measure really really really big distances in space.

So, you know how we can see stars in the sky at night? Well, those stars are really really far away from Earth. So far, in fact, that it would take a really really long time to travel there. But because light travels super fast (almost 299,792,458 meters per second, to be exact), we can use it to measure how far away those stars are.

A light-year is the distance that light can travel in one year. That's how fast it is! And one light-year is a REALLY long way - it's about 5.88 trillion miles (9.46 trillion kilometers). That's a number so big that it's hard to even say!

So when scientists talk about the distance between different stars, they often use light-years. For example, the closest star to our own sun is called Proxima Centauri, and it's about 4.24 light-years away. That means it would take light over 4 years to travel from Proxima Centauri to us.

So that's what a light-year is, kiddo - a way of measuring really really big distances in space using how long it takes for light to travel. Cool, huh?