The term “Super Blue Blood Moon” describes a rare alignment of three separate lunar phenomena occurring simultaneously. This triple coincidence results in a single, dramatic celestial event, noted for its unusual combination of size, timing, and color. It is not a formal astronomical classification but a popular term for a full moon that meets three distinct conditions. The rarity of this occurrence stems from the lack of synchronicity between the Moon’s orbital mechanics and the human calendar.
Defining the Components of the Alignment
The “Supermoon” component refers to a full moon that occurs when the Moon is near its closest point to Earth in its elliptical orbit, known as perigee. This close proximity causes the Moon to appear up to 14% larger and 30% brighter than a full moon at its farthest point (apogee). Supermoons are relatively common, happening about three to four times a year.
The “Blue Moon” is the second full moon to occur within a single calendar month. Since the lunar cycle is approximately 29.5 days, this calendar quirk happens roughly once every 2.7 years. This definition is a modern interpretation, as the original definition referred to the third full moon in a season that contained four full moons.
The final component, the “Blood Moon,” refers to a total lunar eclipse. This occurs when the Earth passes directly between the Sun and the Moon, casting a shadow over the lunar surface. During the eclipse, sunlight is refracted through the Earth’s atmosphere, scattering away the blue light. The remaining longer-wavelength red and orange light is then projected onto the Moon, giving it a reddish-brown hue.
The Astronomical Rarity of the Coincidence
The infrequency of the Super Blue Blood Moon arises from the need for three independent astronomical cycles to align perfectly. Each phenomenon operates on its own distinct period, making their simultaneous convergence a complex event. The Supermoon is governed by the Moon’s orbital period around the Earth, approximately 27.5 days.
The Blood Moon (total lunar eclipse) is linked to the Moon’s orbital plane alignment with the Earth and Sun, occurring near the line of nodes. Total lunar eclipses happen once or twice a year, but they must coincide precisely with the other two events. The Blue Moon, conversely, is governed not by celestial mechanics but by the Gregorian calendar, based on the non-uniform length of calendar months.
For the Super Blue Blood Moon to happen, the Moon must be at perigee, at the correct orbital node for a total eclipse, and be the second full moon in a calendar month. The lack of a common period between the Moon’s elliptical orbit, the eclipse cycle, and the calendar month means the triple alignment does not follow a predictable pattern. The calendar factor introduces an irregularity that makes the recurrence interval highly irregular, often spanning decades.
Historical Occurrences and Future Predictions
The most recent and widely observed Super Blue Blood Moon occurred on January 31, 2018. This event was notable because it was the first time this specific combination was seen in North America since 1866 (152 years prior). Before 2018, a similar trifecta occurred in December 1982, though visibility varied by location.
The complex, non-repeating nature of the three cycles means that predicting the next occurrence requires meticulous astronomical calculation. The next Super Blue Blood Moon is predicted to take place on January 31, 2037. This roughly 19-year gap reflects the longer-term cycles of lunar motion.
The alignment of these three independent factors is not a common annual or decadal occurrence. While Supermoons and Blood Moons appear frequently, the addition of the calendar-based Blue Moon requirement makes the combined event truly infrequent.