Surface brightness

Surface brightness is like how bright a light bulb looks when you look at it. When you look at a light bulb, you can tell how bright it is by how much light is coming out from the bulb. Surface brightness is kind of like that, but it looks at how bright something looks from a distance - like a star in the night sky. Surface brightness measures how much light comes out of an object, like a star, when you look at it from a certain distance.