NASA - National Aeronautics and Space Administration - In honor of tonight's 'Blue Moon,' astronaut Scott Kelly aboard the International Space Station posted this image

In honor of tonight's 'Blue Moon,' astronaut Scott Kelly aboard the International Space Station posted this image and wrote, "TGIF Here's a preview of tonight's rare celestial surprise. ‪#‎BlueMoon‬ on the rise.‪#‎YearInSpace‬."

'Once in a Blue Moon' typically means rare or absurd. This year, it means tonight! According to modern folklore, the second full moon in a month is a "Blue Moon." But of course that doesn't mean it's necessarily blue. Step outside at sunset, look east and see what color presents itself.

To learn more about 'Blue Moons,' watch: https://youtu.be/XyBp-EYrwTA