Generally, a month only has 1 Full moon. However, once every couple of years, a month will have 2 Full moons. This occurrence is called a "Blue Moon". This usage results from a misinterpretation of the traditional definition of blue moon in the March 1946 issue of Sky and Telescope.
A blue moon occurs only every two or three years, and the term blue moon is used colloquially to mean a rare event, as in the phrase "once in a blue moon".
The apparent colour of the moon, at any time of the year, can be affected by atmospheric circumstances. Volcanic eruptions and exceptionally large fires can leave particles in the atmosphere which give the sky, and thus the Moon, a tinge of blue (or other colours).
Read more about Blue Moon: Origin, Early English and Christian Usage, Maine Farmers' Almanac Blue Moons, Visibly Blue Moon, Blue Moons Between 2009 and 2021, Popular Culture
Famous quotes containing the words blue and/or moon:
“That air would disappear from the whole earth in time, perhaps; but long after his day. He did not know just when it had become so necessary to him, but he had come back to die in exile for the sake of it. Something soft and wild and free, something that whispered to the ear on the pillow, lightened the heart, softly, softly picked the lock, slid the bolts, and released the prisoned spirit of man into the wind, into the blue and gold, into the morning, into the morning!”
—Willa Cather (1873–1947)
“The faery beam upon you,
The stars to glisten on you,
A moon of light
In the noon of night
Till the firedrake hath o’er gone you.”
—Ben Jonson (1572–1637)