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Over 250K people have volunteered to help SETI sift through data for signs of extraterrestrial intelligence. The 2-year SETI@home project will distribute screen-saver software in another month, turning the Internet into the world's largest supercomputer. SETI@home will be 10 times as sensitive to weak signals as previous analyses of data from the 1,000-foot radio telescope at Arecibo, Puerto Rico. . [Bill Park , 19Mar99.]

Computists have sent me references about the definition of "blue moon." I don't know when the term originated, but it seems that the Maine Farmers' Almanac (also used by fishermen) was an influential keeper of the calendar. Each of the twelve moons of a normal year has a name and associated activity. Sometimes there's a 13th full moon, and at least one month has to have two of them. That's what I've been calling a blue moon. This usage dates back 53 years, to an amateur astronomer/author who assumed this definition without checking it out (Sky & Telescope, Mar46). An editor repeated the error in 1950, and the StarDate radio program popularized it in Jan80. You can find a calculator for this definition (which hits about 41 times/century, or every 2.44 years on average) at . (The date of a full moon can depend on which time zone you're in. The US had two blue moons in 1961 except for the Eastern time zone, according to .)

The Maine Almanac's definition is quite a bit more complex. They use a "tropical year" (starting on the winter solstice) and "dynamical mean Sun" to divide each year into four equal seasons. When a season has a fourth full moon -- about 7 years in 19, or every 2.7 years on average -- the third one falls outside the usual naming system and is called Blue Moon. Such events fall a month before a solstice or equinox, on the 20th-23rd day of November, May, February, or August. There is no such blue moon in 1999, with the next one coming on 19Feb00. . [John Hartman, Alan Rosselet, and Ron Zacharski, 01Apr99.]

(I can't deal with all this, and intend to ignore blue moons from now on. However, this exchange has led me to believe that we do need an discussion group.)