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Illusion  Summer is a good time to spot giant moons very near
the horizon. It's the season for the mysterious moon illusion.
see captionJune 24, 2002: Sometimes you just can't believe your
own eyes.  Tonight is one of those times. Go outside around 9:00
p.m. and look east. Rising above the horizon you might see a
giant moon. Bright, very likely pink or orange, and swollen. The
moon is real, but its surprising diameter is an illusion--the
"moon illusion."  The moon illusion is a well-known trick of the
eye: a low-hanging moon looks unusually big. The moon is really
the same size (0.5 degrees wide) no matter where it appears in
the sky--photographs prove it--but the human eye and brain tell
us differently.  Above: A time-lapse sequence of the moon rising
over Seattle. To the camera, the moon appears to be the same
size no matter what its location on the sky. Credit and
copyright: Shay Stephens.  subscription image Sign up for
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