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Desert Diary
Physics/Blue Moon


Few sights are as beautiful as a full moon rising over the desert landscape. Usually seen once a month, we'll have to wait almost 2 years to see a month with a second oneā€”the so-called "blue moon".

Blue moons go way back. A pre-Elizabethan reference was "Yf they say the mone is blewe, We must believe that it is true", and that meant "never". In the 16th century, comics talked of a moon of green cheese, and an unusual full moon with a thin illuminated edge was a blue moon, being as rare as an old cheese with blue mold. In the last century, Rodgers and Hart penned, "Blue moon, you saw me standing alone...", and Monroe's "Blue Moon over Kentucky" became that state's official bluegrass song.

Today, the phrase, "Once in a Blue Moon", is commonly understood as not very often and has come to be linked with a second full moon within 1 month. In the 1200 months making up a century, only 41 will be so graced. So mark July, 2004, on your calendar.
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Contributor: Florence E. Schwein, University of Texas at El Paso.

Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.