The "Blue Moon" happens July 31. There are, in fact, two definitions for a blue moon. According to the more recent definition, a blue moon is the second full moon in a calendar month. For a blue moon to occur, the first of the full moons must appear at or near the beginning of the month so that the second will fall within the same month (the average span between two moons is 29.5 days).
The older definition, which is recorded in early issues of the Maine Farmer's Almanac, states that the blue moon is the third full moon in a season that has four full moons. Why would one want to identify the third full moon in a season of four full moons? The answer is complex, and has to do with the Christian ecclesiastical calendar.
So, how did July's full moon get its name? It is normally the month when the new antlers of buck deer rush out of their foreheads in coatings of velvety fur. It is also often called the Full Thunder Moon, since thunderstorms are common during this time of the year. Another name for this month’s Moon is the Full Hay Moon.
Full Moon names date back to Native Americans in what is now the Northern and Eastern United States. The tribes kept track of the seasons by giving distinctive names to each recurring Full Moon. Their names were applied to the entire month in which each occurred. There was some variation in the Moon names, but in general, the same ones were current throughout the Algonquin tribes from New England to Lake Superior.
A Full Moon rises at about the same time the Sun is setting. Since the length of daylight is about 15 hours and six minutes tomorrow, the Full Moon will rise later and set earlier this time of the year. In addition, the Full Moon will appear lower in the sky since it won’t be visible nearly as long as during the mid-Winter nights.
For example, the Moon rises at 7:57 Wednesday evening and sets at 6:07 Thursday morning. That means the Moon will be visible for 10 hours and 10 minutes. Conversely, six months from now in January when the amount of daylight is at a minimum, the Full Wolf Moon will appear higher in the sky and be visible for about 17-and-half-hours. That’s over eight hours longer than this time of the year!
Paul
