Most of us know the Blue Moon as the second full moon in a month. This “extra” full moon in a month occurs roughly every 2-3 years, however the Blue Moon was defined differently before the early 20th century. In most years, there are 12 full moons in the calendar year, or 3 full moons in each season. The moons were refered to as the ‘first moon’, the ‘middle moon’ and the ‘last moon’. Those years with 13 full moons, there is an extra moon in one of the seasons. The third extra moon in the season was called the Blue Moon. Today, November 21, 2010 is a full moon day. This full moon is a Blue Moon by the old definition. The next full moon of the year is December 21st. If the winter solstice is December 21, how can the moon in November be a Blue Moon? Technically, the full moon on December 21st occurs hours before the earth reaches the solstice point in her orbit, so that full moon is the ‘last moon’ of the autumnal season.
Be the first to start the conversation!