Angular size

Imagine you have a big pizza and a small pizza, but they're both really far away. Even though the big pizza is bigger than the small pizza, they might look the same size to you because they're so far away.

Now imagine that you get closer to the pizzas. As you get closer, the big pizza looks bigger and the small pizza still looks small. This is because the amount of space the pizza takes up in your field of vision, or your "view," changes as you get closer.

Angular size is a way of measuring how much space an object takes up in your view, or your field of vision. Imagine holding your arms out straight in front of you, with your thumbs touching and your fingers spread out. The distance between your two thumbs is about 2 degrees of angular size.

So, as you get closer to an object, its angular size gets bigger because it takes up more space in your view. And as you move farther away from an object, its angular size gets smaller because it takes up less space in your view.

Scientists use angular size to study things like the size and distance of planets, stars, and galaxies. By measuring the angular size of these objects, they can figure out how big they really are and how far away they are from us.