Two Moons, Two Sizes, Two Colors

October 24, 2013

Two moon 2

: Bill Metallinos; Bill's Web site
Summary Author: Bill Metallinos; Jim Foster

The above two full Moons were shot with the same telescope and camera. The Moon at left was photographed shortly after it rose in August 2010, near the lighthouse of Corfu’s Old Fortress in Greece. This Moon was at apogee -- furthest point from the Earth (252,277 mi or 406,000 km away). At right, the rising full Moon of July 2013 appears to be touching the walls of the New Fortress (also in Corfu). At a distance of 224,936 mi (362,000 km), it was very close to perigee -- closest point to Earth. Since this Moon is about 10 percent closer it appears slightly larger.

The coloration of these two full Moons is attributable to their proximity to the horizon. When the Moon is low in the sky the shorter wavelengths of visible light (violet, blue and green) are effectively removed from our view by the increased path length of the moonlight that reaches our eyes -- increased scattering by air molecules. The scarlet color of the July Moon results from higher amounts of haze and humidity causing even greater scattering of the moonlight.

Photo details: SW ED80 Canon eos 30D camera; 600mm lens; f7.5; ISO 100.