What is a Blue Moon?
August 31, 2012 § Leave a comment
from The Farmers’ Almanac
For more than half a century, whenever two full Moons appeared in a single month (which happens on average every 2 1/2 to 3 years), the second has been christened a “Blue Moon.” In our lexicon, we describe an unusual event as happening “Once in a Blue Moon.” This expression was first noted back in 1821 and refers to occurrences that are uncommon, though not truly rare.
On past occasions, usually after vast forest fires or major volcanic eruptions, the Moon has reportedly taken on a bluish or lavender hue. Soot and ash particles, propelled high into the Earth’s atmosphere, can sometimes make the Moon appear bluish.
Why “Blue” Moon? For the longest time nobody knew exactly why the second full Moon of a calendar month was designated as a Blue Moon. Read the rest.