Tonight's blue moon won't be seen again until 2015
The first blue moon in three years will appear in the night sky Friday, and the next blue moon won't be seen until 2015.
In Los Angeles, the full moon will begin to rise at 7:13 p.m.
A blue moon doesn't mean the moon will actually change color--it's the rare occurrence of two full moons occurring in the same calendar month.
The last time a blue moon happened was on New Year's Eve 2009. The next blue moon will occur on July 31, 2015, according to moongiant.com.
The phrase "blue moon" has been around for more than 400 years, wrote Philip Hiscock, a folklore expert at the Memorial University of Newfoundland, in an exhaustive piece on the origin of the phrase "blue moon" over the years.
But the current meaning was popularized only in the 1980s, he wrote in his piece for Sky & Telescope. Centuries ago, "blue moon" had more of a literary meaning of the absurd, "like saying the Moon is made of green cheese," he wrote.
Hiscock wrote that it was in 1988 when he first heard the term "blue moon" identified as the second full moon in a month, and was asked about it after "radio stations and newspapers everywhere carried an item on this bit of 'old folklore,' as they called it, drawing on an international wire story."
As it turns out, Hiscock concluded, the term was popularized by the radio program "Star Date," broadcast in January 1980. By 1985, the definition was enshrined in "The Kids' World Almanac of Records and Facts," and shortly after that was a question in Trivial Pursuit in 1986.
A NASA article says the original source of the "blue moon" definition came after an amateur astronomer, James Hugh Pruett, was attempting to explain to Sky & Telescope readers in 1946 what blue moons were, trying to interpret a complicated definition in the Maine's Farmer Almanac that was "so convoluted even professional astronomers struggled to understand it."
Next month's full moon will occur on Sept. 30, which is known as the harvest moon, and coincides with the Mid-Autumn Festival, known for the prolific baking of mooncakes in Asian and Asian American communities.
Forecasters expect mostly clear skies in the evening on the coast and in the Los Angeles Basin, but there could be low clouds and fog later in the evening. The valleys are expected to be mostly clear.
-- Rong-Gong Lin II
Photo: A blue moon above the ancient Acropolis hill in Athens. Credit: Louisa Gouliamakilouisa Gouliamaki /AFP /GettyImages