Full Moon Rising Above the Valley of the Moon

Provided by: Christine Churchill
Summary authors & editors: Christine Churchill, Jim Foster

The looming Moon shown above appears to be reclining on the hillside in the foreground. It was photographed from the Valley of the Moon, California on January 18, 2003 at 6:08 p.m., Pacific Standard Time. When the Moon hugs the horizon it gives the illusion that it is of extraordinary size. This is of course not the case, but rather a result of perspective. One of several explanations for the Moon illusion involves the size-distance paradox. It seems that because we know objects such as birds or airplanes appear larger when overhead than when close to the horizon, celestial objects positioned near the horizon should look smaller too. However, for really distant objects, this isn't so. Our brains compensate by making us think that the Moon (or Sun) is colossal when located low in the sky. See also the Earth Science Picture of the Day for June 29, 2007.

Photo details: Sony 4.1 megapixel camera (afocal photography) and a homemade Dobsonian 10" telescope, 40 mm eyepiece, shutter speed 1/500, aperture f/2.8.