On Friday, July 31st, Professional astronomers and astronomy enthusiasts will gather to witness a Blue moon that only occurs every 2-3 years. The Blue moon will brighten up the skies and will reach its peak at exactly 6:43 am EDT (10:43 GMT).
According to USA Today veteran weather reporter Doyle Rice, "It (the moon) will not be blue, it will be silver like any other moon."
The Blue moon is a natural phenomenon that occurs every 2-3 years. In the newsletter "What Causes a Blue Moon?" written by Tom Salem, Science Operations Officer of the National Oceanic and Atmospheric Administration, he explained the phenomenon as the second full moon of the month.
"The second full moon of a single month is commonly called the "blue moon" so it is a special full moon. Two full moons in one month happen about every 3 years. The next blue moon after this year will occur in June, 2007. There were 2 full moons during the month of July in 2004. The first occurred on July 2 and the second on July 31. So, the full moon on July 31 was our blue moon."
The term "blue moon" during the time of Shakespeare means "rare," thus the phrase "once in a blue moon" was coined.
In the 1940s, the Maine Farmers' Almanac made occasional reference to a Blue moon, but derived it from a completely different (and rather convoluted) seasonal rule.
The modern day definition of a Blue moon was derived from the interpretation of James Hugh Pruett to the Maine Farmers' Almanac. In his article entitled "Once in a Blue Moon" featured in Sky & Telescope Magazine, Pruett wrote that the Blue moon is the second full moon of a full moon.
The moon can also literally turn blue on certain occasions. According to Science@NASA, we can see the moon turn blue in the events of extreme volcanic eruption, due to the plumes produced by the eruption, as well as when there are wildfires. The plumes are only 1 micron wide and blocks the red light, only letting the blue light pass through, thus giving the moon a blue hue.
