Friday 20 June 2014
The Moon illusion
is an optical illusion in which the Moon appears larger near the horizon than
it does while higher up in the sky. This optical illusion also occurs with the Sun
and star constellations. It has been known since ancient times and recorded by
various cultures. The explanation of this illusion is still
debated. A simple way of demonstrating
that the effect is an illusion is to hold a small object (say, 1/4 inch
wide) at arm's length (25 inches) with one eye closed, positioning it next
to the seemingly large Moon. When the Moon is higher in the sky, positioning
the same object near the Moon reveals that there is no change in size. Source
