NASA has explained in its blog that the Blue Moon appears every two and a half years. After 2020, the Blue Moon will appear in August 2023, May 2026 and December 2028. At the same time, every 19 years, this Blue Moon appears on Halloween night, it is known as Metonic cycle. The Blue Moon comes after the October Harvest Moon. Theoretically it marks the beginning of winter.
According to FarmersAlmanac, the last time the Halloween Blue Moon appeared in 2001 was only seen in the Central and Pacific time zones. However, the upcoming moon can be seen in all time zones, which is quite rare. Reports state that the last Halloween full blue moon was seen in all time zones in 1944.
What happens blue moon
The most common definition of Blue Moon is that when two full moons i.e. full moon falls in a month, the second full moon moon is called Blue Moon. However, another definition states that when there are four full moons in a season, the third moon is called the blue moon.