text: It is an illusion. People tend to perceive objects on the horizon as larger than they really are, but you can destroy the illusion by looking at the horizon upside down. Really! I have tried it. And it is not only the Moon, but trees and buildings too. As you tilt your head more and more things on the horizon start to look smaller. I notice that sideways is enough tilt for me to see things on the horizon as noticeable smaller than when looking upright. The usual suggestion is to bend over and look at the horizon between your legs, but that is just to embarrassing for me so I tilt my head sideways until I am looking upside down to one side of my legs and notice the size changing when I am about half Way to being upside down. Try it, it is easy!