The term Blue Moon is believed to have originated in 1883 after the eruption
of Krakatoa. The volcano put so much dust in the atmosphere that the Moon
actually looked blue in color. This was so unusual that the term "once in a
Blue Moon" was coined. However, Blue Moon was also used in much the same
way we use the term "Harvest Moon". There were twelve names for full moons,
one for each month, and the name Blue Moon was used in years which had 13
full moons. It referred to the third full moon of the four occuring between
an equinox and solstice in that year. A misinterpretation of this led to a
Sky and Telescope Magazine "Star Quiz" in July 1943 followed by an article
in March 1946 which stated that the second full moon in any calendar month
was called a Blue Moon (attributed to the 1937 Maine Farmers' Almanac), and
this definition has now become part of the language.
Full Moons January-March 1999 | |
Eastern Standard Time | Universal Time (GMT) |
January 1, 9:51 p.m. | January 2, 02:51 |
January 31, 11:08 a.m. | January 31, 16:08 |
March 2, 1:59 a.m. | March 2, 06:59 |
March 31, 5:49 p.m. | March 31, 22:49 |
The Blue Moon Page
- including a Blue Moon Calculator
The origin of the term "Blue Moon"
- Sky and Telescope magazine
Folklore of the Blue Moon
Moon illumination for a given year
- U.S. Naval Observatory
Moon Phase Calculator - NASA Marshall Space Flight Center
NSSDC Moon home page
NSSDC Moon fact sheet
Planetary home page