At 6:42 a.m. Eastern Time tomorrow (3:42am local time), you and all of your friends across America will have the opportunity to wake up to a once-in-a-blue-moon experience–that being the presence of an actual blue moon! But, here’s the thing–blue moons aren’t actually blue: While dust particles or the presence of ash in the air can occasionally cause them to look that way, they typically take on a light gray hue. Rather, in astronomical terms, a blue moon is the second full moon in a single month, whereas the norm is for most months to have only one full moon…
Blue Moon 2015: How often is ’once in a blue moon’? | masslive.com: http://www.masslive.com/news/index.ssf/2015/07/blue_moon_2015_when_to_see_thi.html