Blue Moon

Verified Timeline

Lore & Background

The phrase 'blue moon' in the metaphorical sense of a long time dates from the 1820s. The specific calendrical term originated with the 1937 Maine Farmers' Almanac, possibly invented by editor H. P. Trefethen. The almanac's explanation—that an extra moon was called 'blue' and considered unlucky—is unsupported and likely a hoax. James Hugh Pruett misinterpreted the almanac in 1946, leading to the modern definition of the second full moon in a month. The term 'blue moon' for a calendrical event is not from Native American tradition.

In Their Own Story

The song was first recorded in October 1934 by Ted Fio Rito with Muzzy Marcellino on vocals, quickly followed a month later by Frankie Trumbauer & his Orchestra, with vocals by Dick Robertson. Other early recordings included those by Connee Boswell and by Al Bowlly in 1935. The song was a hit twice in 1949, with successful recordings in the U.S. by Billy Eckstine and Mel Tormé. In 1961, "Blue Moon" became an international number-one hit for the doo-wop group the Marcels, on the Billboard 100 chart and in the UK Singles Chart.

Reader's Guide

A calendrical blue moon (by Pruett's definition) occurs 7 times in every 19 years, or about once every 2 or 3 years. It can happen in any month except February. A visually blue moon is rare and unpredictable, caused by particles of about 1 micrometre in diameter scattering red light. Such events have been recorded after volcanic eruptions (e.g., Krakatoa in 1883, El Chichón in 1983, Mount St. Helens in 1980, Mount Pinatubo in 1991) and forest fires (e.g., Sweden and Canada in 1950–1951).

Did You Know?

• The earliest known use of 'blue moon' in the metaphorical sense of a long time is from 1821, in Pierce Egan's Real Life in London.
• The 1937 Maine Farmers' Almanac claimed an extra moon was called 'blue' and considered unlucky, but there is no evidence for this.
• A blue moon can appear green; after the 1883 Krakatoa eruption, observers saw a green crescent moon.
• The phrase 'once in a blue moon' is recorded from 1833.