Image above: A Blue Moon is when there is more than one full moon in a month.

Sometimes people say, "once in a blue Moon." Does this mean that sometimes the Moon changes colors? No. Will you look up in the sky one night and see a blue Moon? Probably not. Well, what does it mean? "Once in a blue Moon" means not very often. A blue Moon is the second full Moon in a month. There are about 29 days from one full Moon to the next.

There was a full Moon on July 2. The next full Moon was on July 31. This was last year 2006. The Moon you saw was the color of your jeans? Probably not.

"Blue Moon" is just a saying from long ago.

Now we say "once in a blue Moon" when something hardly ever happens.

The last blue Moon (before 2006) was in 2001. The next one will be in May 2007.

If someone asks you, "When do you clean your room?" "Once in a blue Moon" is not a good answer.

Which month do you think will never have a blue Moon? February, because it only has 28 days (sometimes 29).