Blue Moon 2013: What Is a Blue Moon? August 2013 Full Moon 3rd of Season
August 21, 2012 (CHICAGO) (WLS) -- Stargazers got a rare sight late Tuesday - a blue moon - but it often is not really blue.
On Tuesday, it looked more orange. It's the third full moon this season. Sometimes it's called an alternative moon or seasonal blue moon.
According to common folklore, based on a mistake printed in Sky and Telescope magazine in 1943, the blue moon occurs when there are two full moons in a month. Full moons are separated by 29 days, while most months are 30 or 31 days long; so it's not often two fall in one month. But in this case, the third moon of a four-moon season, the real original definition of a blue moon, has occurred.
According to NASA.gov, "Squeezing a second full Moon into a calendar month doesn't change the physical properties of the Moon itself, so its color remains the same... However, be aware on rare occasions it can happen."
What does it take to get an actual blue, as in the color blue, moon? "A truly-blue moon requires a volcanic eruption," according to NASA. That's when smoke from a volcanic eruption here on earth rises up, making the moon look hazy and, well, blue.
"Certain forest fires can do the same trick," according to NASA.
Those truly blue moons are even rarer than the other, already rare, blue moon. The next of which will occur on July 31, 2015.
- Bitter cold expected to last through the weekend
- Nelson Mandela condolence books open, tribute held 33 min ago
- ABC 7 Special: Monday Night Monsters
- ABC7 Weather Forecast
- Schaumburg woman missing since October found
- Vigil held for Khaseem Greene's cousin killed in NJ
- Chinese-American Service League kicks off 35th anniversary 20 min ago
- Illinois pension bill private signing questioned
- Chicago speed cameras added on North, South Sides
- Girl, 13, charged in Olympia Fields fatal crash that killed boy
- Loop attorney, nephew charged with sex assault of man
- 'Heart and Soul' - Saturday, Dec. 7, 6 p.m.
- Photos: Christmas Tree Ship arrives at Navy Pier
- abcnews: Made in America 2013: Gift Ideas
- Nelson Mandela condolence books open,...
33 min ago