A blue supermoon, which combines the phenomena of a supermoon and a blue moon, occurs roughly once every 10 years on average. The timing is irregular and can vary, with intervals as long as 20 years, but about a decade is typical between occurrences
- A supermoon happens when the full moon is at or near its closest point to Earth, making it appear larger and brighter than usual. Supermoons occur more frequently, about three to four times per year
- A blue moon can be defined in two ways: either as the second full moon in a single calendar month (monthly blue moon) or as the third full moon in a season that has four full moons (seasonal blue moon). Blue moons happen about every two to three years
- The blue supermoon is rare because it requires both conditions to coincide: a supermoon and a blue moon happening at the same time. This rarity leads to the roughly once-a-decade frequency
For example, a blue supermoon occurred on August 19, 2024, and the next one is expected around 2032
. Supermoons themselves are more common, but the combined event is special and infrequent. In summary, blue supermoons happen about once every 10 years on average, though the exact timing can vary significantly. Supermoons occur several times a year, and blue moons every few years, but their overlap is rare
