Blue moons (was Halloweenie things)

[Vanessa]

--- In HPFGU-OTChatter at y..., "David" <dfrankiswork at n...> wrote:
> Aleks wrote:
> 
> > A blue moon is the second full moon in one calendar month ie/ 1st 
> full
> > moon at beginning of October so the one last night was a 'blue' 
> moon.
> 
> Thank you - but why blue?
> 
> D

originally 'blue moon' meant 'never'  - I believe from a poem about a 
blue moon, so the colour is not significant, save for the fact that 
the moon is never blue.  The idea that it was the second full moon in 
a month, etc, was tacked on later.

I believe there is a Straight Dope column about it....

*goes searching*

yes, here it is:
http://www.straightdope.com/classics/a1_172.html