We just learned about the Lunar Phase.
When people talk about a blue moon they don't mean that the moon actually turns blue!
A full moon comes around every 29 days, so there is usually only one full moon per month.
If there are two full moons in the same month, the second one is called a blue moon.
This doesn't happen very much, so there is a saying "once in a blue moon" that means not very often.
(from: wikipedia - blue moon)
Kid Facts - Blast from the past: Jupiter
