You’ve probably heard the phrase, "...once in a blue Moon." The expression refers to something that doesn’t happen very often. But, what does it really mean? And, does the Moon actually turn blue?
The full lunar cycle takes 29.5 days, so typically there aren’t two full Moons within the same calendar month of 30-31 days (except for February). But, when it does happen twice, tonight and again August 30, we consider the second occurrence a blue Moon.
The Moon doesn’t really turn blue, but if you wish upon a star, it might. ;-)
Photo credit: NASA/Uit Science Team - Photo of the Moon in ultraviolet light by the Ultraviolet Imaging Telescope carried by the Astro-2 Shuttle mission in March 1995.