Bortle scale

The Bortle Scale is like a map of how bright the sky looks at night. When you look up at the sky at night, you'll see lots and lots of stars twinkling up above you. But some places have more stars to see than others, depending on how much light there is around you.

The Bortle Scale helps people figure out how much light pollution (that's when there are too many lights around and it makes it hard to see the stars) there is in different areas. It's kind of like a rating system, with numbers from 1 to 9.

A place with a Bortle Scale rating of 1 is super dark, with no lights around at all, so you can see all the stars in the sky really easily. But a place with a Bortle Scale rating of 9 is really bright, usually because it's in a big city with lots of lights, so you can't see as many stars.

Scientists and astronomers use the Bortle Scale to figure out where the best places are to look at the night sky and see all the stars. They'll go to places with a low Bortle Scale rating, like a dark desert or a quiet forest, to get the best view of the stars.