blue moon

[iantobach]

did anyone know that the second full moon in this month is called a "blue moon"- originating the rare(ish) event and term "once in a blue moon"" :moon: :moon:??

[Robd]

Well you live and learn - I always thought that it referred to the wife buing a round

[Vega]

Anyone know where the term 'Blue Moon' came from? What's blue got to do with it ? :scratch:

Vega

[Astroman]

Here we go.

Actually, it's a bit more complex than that, but the current term refers to two full moons in a month.

Previously, and more accurately, a "Blue Moon" occurred when there were 4 full moons in a 3 month lunar cycle, which was based on the equinoxes and the relative positions of the Sun and Moon. Sky and Telescope magazine, back in the 1970's made this mistake once and has had to live with it since. They take credit/blame for this every year and explain the discrepancy, but since all the meteorologists have taken up on it, it's kinda stuck.

The "new" blue Moon occurs nearly every year while a "true" blue Moon happens ona cycle of 17 years, with the same period of eclipses.

http://www.infoplease.com/spot/bluemoon1.html

[The Warthog]

Well, thanks for clearing that up! I've been using the newer terminology for years, but I didn't know better, eh? Years ago I took my kids out on the front step to show them the blue moon. They spent a while trying to convince themselves that it was maybe a little bit blue, until I told them what it meant.

So, when is the next true blue moon?