From the ABC 7 Weather team

Blue Moon, Full Moon both appear on Aug. 20

August 20, 2013 - 10:00 AM
Text size Decrease Increase

If Tuesday night's full moon is the first of the month, how can it be "blue?"

As I was checking our WeatherBug cameras for good views of the fog this morning, I spotted the nearly full moon in Ijamsville and was reminded that not only is the moon “full” Tuesday, it is also “Blue.” Here is a cool timelapse of that moon and fog between 5:30 and 8:30 a.m. You’ve heard the term before, you’ve heard the song, and you’ve probably even used those words yourself when describing something out of the ordinary. But, Tuesday’s “Blue Moon” means something you likely didn’t know before reading this article.

Most of us describe a Blue Moon in terms of astronomy, as the second full moon in a calendar month. This happens seven times out of a 19-year moon cycle.

But, wait! At 9:45 p.m., we saw the only full moon in August, so how can this be true? It all started by a simple mistake made in Sky and Telescope magazine decades ago.

And the definition we use now for a Blue Moon is relatively recent. Previously, moons would be assigned a name based on their appearance in order during each season.

For example, in the summer months the first moon would be called the early summer moon, the second moon called the mid-summer moon and the last moon of the summer season would be called the late summer moon.

But, on occasion, there would be a fourth moon during that period. So, in order to keep the name of the last moon in the season as the “late” moon, the third moon of the season in a four moon cycle would be called the “Blue” moon. That is what we experienced Tuesday. Confused? More in depth at Sky and Telescope's website.

If you took any great photos of the moon, we'll put them on Good Morning, Washington.  Please post them on our Stormwatch7 facebook page or send them to me on twitter @JacquiJeras

comments powered by Disqus