Summer Blue Moon
Each calendar month includes a full moon, but since the lunar cycle and calendar year are not perfectly synchronized, about every 3 years, a month includes two nights with a full moon. The first full moon of this month was in Capricorn on July 1st. Your calendar likely says that the first of two July 2015 full moons falls on July 2. The first full moon of July falls on July 2 at 2:20 UT. That is July 1 at 10:20 P.M. EDT, 9:20 P.M. CDT, 8:20 P.M. MDT or 7:20 P.M. PDT. So, for us in the U.S., the full moon happens on July 1.
Today is the phenomenon well-known as “blue moon”.
But the sense of “blue moon” has different in the last 200 years, this name being used firstly for the unusual circumstances in which the full moon appears 4 times in a season in which there were astronomical, normally its only 3 appearances.
BLUE MOON JULY 2015.
Contrary to its name, the night sky we don’t see a blue moon just the second full moon in this month. The last blue moon happened almost 3 years ago, in August 31, 2012.
Original Blue Moon Definition
The current definition of a Blue Moon was derived from an earlier idea of what a Blue Moon was. This earlier definition says a Blue Moon is when there are 4 Full Moons in a season rather than the usual 3. The Blue Moon is the third full moon out of the four. This definition gets a bit confused and its origins are murky. Many cultures named the Full Moons each month to reflect the seasonal conditions or the times for planting, harvesting. When an extra full moon was thrown in it was referred to as a Blue Moon to keep the Full Moon names constant throughout the year. One school of thought has to do with the naming of the full moons.
Alternative origin could be from the Christian ecclesiastical calendar. This one gets even trickier but basically has to do with the idea that there are typically 12 full moons in a calendar year. The full moons on this calendar were significant markers for determining curtain dates such as Easter. When a 13th Full Moon was thrown into the year it made things messy so giving it a name accepted the calendar to stay on track.
In accordance with the modern folklore, whenever there are two full Moons in a calendar month, the second one is known as “blue”.
Is the moon ever the color blue?
This is a very rare event but it does regularly happen. There are a few registered events when forest fires or ash volcanic eruptions have given the moon a bluish color. As well, the moon can have a blue color on very cold winter nights when ice crystals in the air form a ring around the moon. Of course the idea of the moon being blue is very subjective and left up to one’s own interpretation.