This week we have a "Blue Moon".
Except the moon isn't actually blue unless you live near an active volcano or one of the big fires out west. But interestingly a blue reflection is seen here caused by internal camera lens reflection at slow shutter speed.
So what does "Once in a blue moon" mean?
There is more than one view on the subject. Blue Moon is often used to denote a second full moon in one calendar month. This is the 21st of August so that's not quite possible. The older definition is that it is the third full moon in a season with a rare four full moons. So this summer we have four full moons.
The question of why the scientists who decide these things chose the more common third moon instead of the more obvious choice of the rarer fourth moon remains unanswered.
One more very important question. Which Blue Moon was in Tony Soprano's eyes?
Either way it's fascinating to spend some time looking at the moon on a nice evening.