A blue moon occurs when there’s a second full moon in one calendar month. It won’t happen again until July 2015. The full moon cycle is 29.5 days so a blue moon is uncommon and has come to mean something rare. The moon actually won’t be colored blue.
- Turning Blue: Friday’s Full Moon a ‘Blue Moon’ (newsfeed.time.com)
- Friday’s blue moon coincides with Neil Armstrong service (fox6now.com)