The Ponzo Illusion is an optical illusion that was first
demonstrated by Mario Ponzo in 1913. He suggested that the human mind judges an
objects size based on its background. He showed this by drawing two identical
lines across a pair of converging lines, similar to railway tracks. The upper
bar looked wider because it spans a greater apparent distance between the rails.
Some researchers believe that the Moon Illusion is an example of the Ponzo Illusion, with trees and houses playing the role of Ponzo's converging lines. Foreground objects trick your brain into thinking the moon is bigger than it really is.