Blue Moon: See the Best Photos From NYC to Seattle

There's a reason why "once in a blue moon" is a saying.

By
ALYSSA NEWCOMB and EMILY SHAPIRO
August 1, 2015, 10:34 AM ET
4 min read

— -- There's a reason why "once in a blue moon" is a saying and Friday night proved it.

A blue moon is defined as any time there is a second full moon during a calendar month, according to NASA. While most years have 12 full moons, this year has 13.

Blue Moon: What Makes Tonight's Event So Special

Here are some of the best Blue Moon photos from Friday night, from Washington D.C. to Seattle:

Don't let the name fool you, though. Blue moons are very rarely blue. Most are pale gray and white, resembling a moon on any other night.

A truly blue colored moon can occur on rare occasions, according to NASA, with most being spotted after volcanic eruptions.