A second full moon in a calendar month will occur on May 31 and be best seen at moonrise on May 30. Why is the Blue Moon one of astronomy’s most misunderstood terms?

See the best images of the Blue Moon from around the world as a second dramatic moonrise occurred in the same month in a rare sky event.

Add Yahoo as a preferred source to see more of our stories on Google. This only happens once in a blue moon, literally. May's second full moon is almost here, and not only is it a rare blue moon, but ...

Add Yahoo as a preferred source to see more of our stories on Google. A rare celestial event is set to light up the night sky this weekend, as what is known as a blue moon rises on May 31. But despite ...

A blue moon is not a sign that the moon will look blue. Instead, the phrase usually refers to an extra full moon that does not fit neatly into the calendar. There are two commonly used definitions. A ...