A rare ‘Blue Moon’ is set to light up the sky over Barga this evening

A rare ‘Blue Moon’ is set to light up the sky over Barga this evening. The term refers to the second full moon in a single calendar month. It is only the third Blue Moon in more than two years and the next chance to see one will be in 2015
However, and despite its name, it is not expected to be blue in colour.

According to Nasa: “Most Blue Moons look pale grey and white, indistinguishable from any other Moon you’ve ever seen. Squeezing a second full Moon into a calendar month doesn’t change the physical properties of the Moon itself, so its colour remains the same.”

Fittingly, the full moon will grace the skies on the same day as the private service for Neil Armstrong, the first man on the moon, who died on Saturday 25 in Ohio, aged 82.

But before you go hunt down your old college astronomy textbooks, you won’t find the definition of a blue moon. It truly is fun-filled, accidental folklore – thanks to the Sky & Telescope magazine in the USA.

“This colourful term is actually a calendrical goof that worked its way into the pages of Sky & Telescope back in March 1946, and it spread to the world from there,” says Kelly Beatty, senior contributing editor for Sky & Telescope.

The “Maine rule”: Going back two centuries, the blue moon was defined as the third moon out of four in a given season, according to the Maine Farmers’ Almanacs going back to 1819. (Donald W. Olson, Richard Tresch Fienberg and Roger W. Sinnott, from Sky & Telescope, went searching for the Maine Farmer’s Almanacs to confirm this.)