Why Does The Moon Look So Big On The Horizon?

Yesterday we had a 'Supermoon.' A supermoon is the coincidence of a full moon or a new moon with the closest approach the Moon makes to the Earth on its elliptical orbit, resulting in the largest apparent size of the lunar disk as seen from Earth.
However, the moon never really changes size, and it's simply your brain playing a trick? Find out what The Moon Illusion is, and why it happens!