Coma (optics)

Okay, so when you look through a telescope or camera lens, there are lots of little pieces that help make the image clear. One of these pieces is called a "coma corrector", which is like wearing glasses to help make everything in the picture look sharp.

But sometimes, even with a coma corrector, things can still look a little fuzzy around the edges. That's called "coma" and it happens because the light from far away objects doesn't all hit the same spot on the camera's sensor or your eye's retina.

Imagine you're drawing a picture with crayons. Sometimes, when you color in with the crayon, it's not all perfectly smooth, right? There might be some marks or bumps on the paper that make it look a little rough. Well, that's kind of what happens with light when it hits a lens - there are little bumps and curves that make it hard for all the light to hit the same spot.

So, when you're looking at a picture of a star in the night sky or trying to see a distant planet through a telescope, sometimes the edges of the image might not look as sharp as you'd like because of this bumpiness. But don't worry - scientists and engineers are always working on ways to make the images clearer for us to see!