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. [More]

This weekend's full moon hangs lower in the sky than any other full moon of 2007, so the Moon Illusion is going to be strong. What makes the moon so low? Consider the following: The sun and full moon lie on opposite sides of the sky. They are like a see-saw: when one is high, the other is low. Because the summer solstice was just last week (June 21st), the sun is near its highest point in northern skies. The full moon is correspondingly low.