[Keri]

Originally Posted by sphelps

Moon illusion, the moon always seems larger in angular size when it is near the horizon than when it is high in the sky. In addition the moon does vary in angular size due to the eccentricity of its orbit. When the moon is closest to earth it obviously appears larger.

Originally Posted by BC Mosaic

Read the caption below the photograph in this link:
http://antwrp.gsfc.nasa.gov/apod/ap071025.html
Sphelps has the right answer as well.

Thanks! I remember someone giving me an explanation years ago but I couldn't remember it, that's it