A Blue Moon itself is not a distinct phase of the moon that lasts a specific length of time; rather, it is a term used to describe the occurrence of an extra full moon within a given time period. Typically, a Blue Moon refers to either the second full moon in a calendar month or the third full moon in a season that has four full moons. The full moon phase, including a Blue Moon, appears fully illuminated for about three days, from the evening before the peak full moon through the morning after, as the moon's brightness remains nearly full during this period
. The Blue Moon does not last longer than a regular full moon phase. In summary, a Blue Moon lasts roughly the same length as any full moon—about three days of near-full illumination—though the exact moment of full moon is instantaneous. The term "Blue Moon" refers to the timing of the full moon rather than its duration or color
