Blue Moon

When someone says "Once in a Blue Moon," you know what they mean:  Rare, seldom, even absurd. This year it means August 31^st.

For the second time this month, the Moon is about to become full.  There was one full Moon on August 1^st/2^nd, and now a second is coming on August 31^st.  According to modern folklore, whenever there are two full Moons in a calendar month, the second one is "blue."

Watch the following video by the NASA and answer the following questions:

• What do blue moons symbolize in literature?
• In which occasions can the moon turn blue?
• When does the moon turn red?

Now watch the following video by the BBC to learn some more idioms related with the colour 'blue'.