Published: 2007-05-13 12:32:26
Updated: 2007-05-13 12:32:26
Posted May 13, 2007 12:32 p.m. EDT
By Deb Murphy
MIKE MOSS SAYS: I have to admit, this one has me stumped. I looked around a bit and can't seem to find any news article references to something strange about the moon on May 2nd, and there doesn't appear to be anything unique about that night in an astronomical sense. It was the first full moon of this month, and there will be a second on the evening of May 31st. One of the definitions sometimes used for a "blue moon" is the second full moon in a single calendar month, but even that applies to the next full moon and not the one on May 2nd. I did see another message asking why the moon appeared deep red on the evening of May 2nd. I assume this was from someone who saw the full moon just as it was rising or setting. On May 2nd, we'd had a couple of hot and breezy days in which we likely had a fair amount of dust and some haze in the sky, though not enough to significantly restrict visibility near the surface. When the moon is viewed at a low angle above the horizon it will appear yellow or reddish due to preferential scattering of short wavelengths (the blue end of the spectrum) of light by the air along the path the light passes through, leaving a reddened appearance. This effect is enhanced when there are additional scatterers in the sky in the form of dust, haze, and/or other pollutants of the right size distribution, and can result in a very rich orange or red-orange color that diminishes as the moon rises to higher angles where its light passes through much less air on the way to the viewer's eye.