Astronomy Picture of the Day

Explanation: The brilliant full Moon might not have looked quite like this to skygazers this week, but the image is a mosaic of 18 digital frames recorded on December 9th at 3:30 UT. At that time, the Moon was only about seven hours past its exact full phase or time of maximum illumination as viewed from Earth. Here, the pixel values corresponding to light and dark areas have been translated in reverse, or inverted, producing a false-colour representation reminiscent of a black and white photographic negative. Normally bright rays from the large crater Tycho dominate the southern (bottom) features as easily followed dark lines emanating from the 85 kilometre diameter impact site. Normally dark lunar mare appear light and silvery. Traditionally, astronomical images recorded on photographic plates were directly examined in this negative colour scheme, which can help the eye pick out faint details.