A “Blue Moon” is when a Full Moon occurs twice in one month, usually in August of most years. It has nothing to do with the color. The phrase “Once in a Blue Moon” is prescribed in it’s rarity, which is actually not that rare. A Blue Moon may also occur seasonally, between the Equinox and Solstice seasonally. Usually, this occurs in the month of August. This summer of 2013 has been somewhat unique in that we have have experienced two Supermoons in May and July, and one Super Super Moon in June. This relates to the moon being at or near it’s perigee, or closest point to Earth in it’s orbital mechanics. A Blue Moon relates to it’s simple timing of being a Full Moon, in a certain time duration. At this posting, the next Full Moon is August 20th, 2013. That would be near right now, since it is 12:25 am EST here in Charlotte, N.C., which it is now 99% full. By moonrise tonight, it will be 100% full. So tonight, you will see a normal size Full Moon, not enlarged like a Supermoon, but a Blue Moon, which is the second Full Moon this month and also as it happens a “seasonal full Blue Moon”.
(don’t know the source of this bar, credit Yahoo!)