Tomorrow marks the second full moon in the calendar month of August, known as a “blue moon”. It’s not really that rare an event, as we discussed yesterday when talking about “other” full moons … sort of. It’s definitely part of American folklore, though, thanks to its romantic musical history.
I was reminded by the great Phil Plait of an interesting fact about full moons. We know that the Moon is “tidally locked” to Earth, always showing the same face since its rotation matches our own. But it’s not perfect. Thanks to a something called lunar libration, the Moon sort of oscillates in its elliptical orbit, and we are able to see slightly more than half its face throughout the year.
It’s illustrated in the GIF above (an even better one here that was too big to post), but if you want to see some HD video action showing you the phase of the moon in every hour of 2012, take a deep breath and head over to the Bad Astronomy blog.
(via Discover Magazine, image via Wikipedia)