COLUMBIA — Is that white ball in the sky really a blue moon?
Yes, but it's a seasonal blue moon — the third of four full moons in one season, according to Sky & Telescope. A traditional blue moon is the second full moon in one month.
"This blue moon coming up (Tuesday night) is probably a real definition of a blue moon," said Val Germann, former president and current secretary and treasurer for the Central Missouri Astronomical Association. "This is sort of the extra full moon within the season."
Seasonal blue moons occur every couple of years, said professor Angela Speck from MU's Department of Physics and Astronomy.
"Blue moons are not common, but they're not really rare," Speck said. "This isn't anything crazy."
The phrase "once in a blue moon" dates to the middle ages or even before.
"The moon can turn blue when there are atmospheric particles," Germann said. "It's possible that a long time ago, one of these events occurred so the name stuck. It's kind of lost in time. No one knows actually."
Newspapers, TV stations and radio stations still debate the term's meaning, according to Sky & Telescope. In the ancient world, a full moon was important because it provided light, Germann said. Sailors navigating the seas at night especially benefited from a full moon's extra wattage.
"Today we don't care because we've got computers and cellphones and GPS," Germann said. "We always know what time it is and where we are. We've got too many things now to pay attention to the moon."
Germann thinks taking a break from bright screens and endless Web pages to see the moon Tuesday night, or even Wednesday night when it's not technically full, will be well worth it.
He plans to photograph the moon Wednesday night from the MU Physics Building. The observatory, on the building's fifth floor, will be open to the public from 8 to 10 p.m. Wednesday.
"The most dramatic views are from places where you can see the whole horizon," Germann said. "It will be very dramatic (Wednesday) night because the sky will be darker."
Germann suggests staking out the top of a parking garage, or any high place, to watch the moon rise about 8:40 p.m.
"Early in the evening, it usually looks really cool," Speck said.
Speck is more excited for Comet ISON, which is expected to be visible to the naked eye in early November. Maybe Frank Sinatra and Elvis Presley should have sung about comets instead. Unlike a blue moon, ISON is a "once-in-a-lifetime thing," Speck said.
Mostly clear skies are forecast for Columbia on Tuesday and Wednesday nights, according to the National Weather Service.
Supervising editor is Elizabeth Brixey.