Thursday, July 7, 2011

The Moon Illusion

I can remember as a kid being in the backseat of my parent's car, driving home at night and looking out the window at that bright, round moon. I remember thinking "why is the moon following me home?" I later learned that the moon is just so big that we can see it from pretty much anywhere, at anytime. Now a new thought has been brought to my attention: the moon looks closer some nights than it does others. Does the distance between the moon and the earth decrease? No, it's all about perception. When the moon is closer to the horizon it looks closer to the earth because it seems like it is surrounded by the earth and its objects. However, when high in the sky, the moon appears smaller because it is surrounded by the endless expanse of sky. This is also known as the angular size contrast theory. The objects on the horizon are small compared to the moon, and the moon is small compared to the open sky.

1 comment:

  1. When I read this in the book I was just going "huh?..." When the moon is really big on some nights I always just thought that it was closer to the earth's surface. After taking this course it just seems like everything that you encounter and question is all about perception.