Lunar Corona, Mars and Beehive Cluster
May 24, 2010
The photo above shows the Moon framed by a compelling corona as well as ruddy Mars and the dim Beehive Cluster of stars (M44). It was taken from Turin, Italy on April 21, 2010. Even when the Moon just enters the waxing, gibbous phase, as it did this night, it’s nonetheless sufficiently bright to “ignite” atmospheric optics, such as this corona. Coronas are diffraction phenomena that form when sunlight deflects off tiny water droplets in mid-level clouds. A corona's rings are essentially interference rings of overlapping colors. Note that the ring sequence repeats colors; the innermost ring is blue. Because the rings of coronas aren't polarized, no reflections are involved.