July's once in a blue moon: rare 'extra' moon visible tomorrow

Tomorrow brings with it a blue moon, which, you may be disappointed to find out, isn't actually a blue-colored moon. Rather, it is an "extra" full moon that only happens in some years, hence the term, "Once in a blue moon". This year, 2015, is one of the special years with an extra full moon, in that every month has had (and will have) one full moon, which is typical, with the exception of July. In total, 2015 will have had 13 full moons instead of 12.

Every month of the year has a full moon, but this July is special. On July 2 there was a full moon, and now tomorrow — July 31 — will bring yet another full moon. This second so-called extra moon is the blue moon, and traditionally has been used in reference to things that happen rarely.

Last month the full moon happened on June 2, and next month the full moon will happen on August 29, followed by September 28, October 27, November 25, and Christmas. Next year will not include a blue moon — they happen about every two-and-three-quarters years (2.71 years, more or less).

It is possible the Blue Moon will have a blue tinge in your location, but don't get your hopes too high. If the weather is in your favor and you want to see the full moon when it is, by the most proper definition of full moon, at its fullest, you'll need to be outside at 6:43 EDT.