In this handout provided by the National Aeronautics and Space Administration (NASA), a second full moon for the month of July rises behind the dome of the U.S. Capitol on July 31, 2015 in Washington, DC. In recent years, people have been using the name Blue Moon for the second of two full moons in a single calendar month. An older definition of Blue Moon is that it is the third of four full moons in a single season. (Photo by Bill Ingalls/NASA via Getty Images)
