Disclaimer: this post has nothing to do with backyard biology.
August 31 was our second full moon of the month, therefore, it was a “blue moon”, a rare event that occurs so infrequently that we make a big deal of it. It also happened to be an exceptionally clear night, so the moon’s features were extra sharp, even with just a little telephoto lens.
We haven’t had a blue moon for two years, and they only occur on average about every two and one-half years, so the analogy of “once in a blue moon” is a good descriptor of a rare event.
Although the moon itself does not take on a different hue in its “blue” state, making it blue, or yellow, or orange (in Photoshop) does enhance its features.
Blue Moon
A yellow cast shows the craters and pitted surface well.
Blue moons were originally defined as the third full moon in a season with four full moons (quarter of a year). Smoke and dust in the air can refract the red light making the moon appear bluer, which apparently has occurred several times following large volcanic eruptions (e.g., Mt St Helens).
Photos of the blue moon from around the world at:http://www.dailymail.co.uk/sciencetech/article-2196661/Blue-Moon-August-2012-Rare-calendar-phenomenon-occurs.html?ito=feeds-newsxml
(Airport in Rio de Janeiro)
The next blue moon is predicted for August 21, 2013, and the next time there will be two blue moons in one year will be 2028. Twice in a blue moon — rare indeed!
Back Yard Biology 
Interesting photos, and great info. If I knew any of this stuff before, I’ve long forgotten it. I did hear my husband say something about a blue moon the other day, but wasn’t paying any attention. I do know the moon was as big on August 31 as I have ever seen it. It was a sight to see as it rose that evening.