Blue moon for New Year's Eve, 2009
NINETEEN years ago Fraser Coasters looked into the sky and saw something up there that occurs just once in a blue moon.
A “blue moon”.
And on New Year’s Eve it’s going to happen again.
“This is a rare thing,” the Chronicle’s consultant astronomer Dave Reneke said yesterday.
“The moon you’ll see won’t appear blue but it’s known astronomically as a blue moon because it’s the second full moon this month.
“December features full moons on the 2nd and the 31st.”
Mr Reneke, editor of Australaisian Science Magazine, said it wasn’t clear where the term blue moon came from.
“But we know it dates back at least 400 years.
“According to modern folklore, a blue moon is the second full moon in a calendar month. Usually months have only one full moon, but occasionally a second one sneaks in.”
Ancient cultures considered the second full moon to be spiritually significant.
Full moons are separated by 29 days, while most months are 30 or 31 days long so it is possible to fit two full moons in a single month.
This happens every two and a half years, on average.
February is the only month that can never have a blue moon by this definition.
There were occasions, he said, when pollution in the earth’s atmosphere could make the moon look particularly bluish. The extra dust scatters blue light.
“For example, the moon appeared blue across the entire earth for about two years after the eruption of Krakatoa in 1883. There were also reports of blue moons caused by Mt St Helens in 1980 and Mount Pinatubo in 1991.”
Dave Reneke said a New Year’s Eve like this year’s one really did come around once in a blue moon. “Look up at the sky on December 31 and see for yourself.”
The next blue moon to occur on New Year’s Eve will not happen until 2028.