Blue Moon 100. 60 x 60 cm. Executed in: Standard, Metallic & Iridescent paints. 'Blue Moon 100' The story: A solar Year is 11 days longer than the calendar year. So approximately once every two years there is an 'extra' moon [a showing of a moon or lunation]. More accurately, there are seven extra so called Blue Moons in every nineteen years [the Metonic Cycle]. So a Blue Moon is, if you like, a 'leap-moon' event. The next one is due 21-11-2010. A Blue moon would be a second full moon in a long calendar month. The third moon in a season with four moons was an misinterpretation perpetrated from a US Farmers' Almanac in 1946. This was only corrected in 1999....A Blue Moon is can also figuratively be an absurdity or an impossibility..."the vicar declared the moon to be blue then it must be so" sort of thing...Ultra-fine smoke/dust particles in the high atmosphere can filter out red-light so making the moon appear to be blue is another possibility.