Back-to-School Sale. Get 15% off Plus and Awesome accounts, now until September 5th.Upgrade now

A blue moon can refer to the third full moon in a season with four full moons. Most years have twelve full moons that occur aproximately monthly. In addition to those twelve full lunar cycles, each solar calendar year contains roughly eleven days more than the lunar year of 12 lunations. The extra days accumulate, so every two or three years there is an extra full moon.

Discover more inspiring photos like this one.

Download the FREE 500px app Open in app