Why Does the Moon Appear Larger on the Horizon?

💡 The Answer

• The Moon does not actually change size - it is an optical illusion called the Moon Illusion
• When the Moon is near the horizon your brain compares it to trees buildings and landscape
• This comparison tricks the brain into perceiving the Moon as larger
• When the Moon is high in the sky there are no nearby objects for reference
• You can test this by holding your thumb at arm length against the Moon at both positions
• The angular size of the Moon remains roughly 0.5 degrees in both cases
• Scientists have studied this illusion for over 2000 years and it still generates debate