Are You Singing “Blue Moon” Yet?

Get ready for the Blue Moon tomorrow, Friday, August 31st. Despite what our mothers taught us, it’s not blue, and it may not be as rare as you think!

“The average time the Moon takes to complete a cycle of phases is 29.5 days. So all months but February can host a second full Moon, if the timing is right. We call these “Blue Moons” and we get one on Friday, August 31. Chances of a full Moon on the first of a month is about 1 in 30, so you’d expect a Blue Moon every 30 months or so — about once every 2.5 years. Not rare. So when the cosmically literate want to reference something that’s uncommon, they **never** say ‘Once in a Blue Moon’.” – Neil deGrasse Tyson, Astrophysicist, Director of the Hayden Planetarium

Of course, a “blue moon” is still used colloquially to mean “a rare event”, as in the phrase “once in a blue moon”. The Farmer’s Almanac defines a Blue Moon as an extra full moon that occurs in a season. One season normally has three full moons, so if a season has four the extra one (actually the third, not the fourth ) was named the blue moon.