On Halloween, the rare Blue Moon will appear in the sky for the first time since 2001. When there are more than one full moon in a month, there is a blue moon. NASA says it coincides with Halloween every 19 years. The moon isn’t really blue, but it will be fully open on Halloween to make things a little spooky. According to NASA, the next time will be in the year 2039 with Blue Moon and Halloween.
NASA has explained in its blog that the blue moon will appear almost every two and a half years. After 2020, there will be blue moons in August 2023, May 2026, and December 2028. On average, the moon meets every 19 years on Halloween, which is called the metonic cycle. The Blue Moon comes after the October Harvest Moon on October 2, and theoretically indicates winter storage time.
According to Farmer Almanac, Halloween Blue Moon was only seen in the Central and Pacific time zones in 2001. This upcoming Blue Moon will be visible in all time zones, and will be reduced even further. The report states that after 1944, the full moon of Halloween did not appear for everyone in all time zones.