Trick or Treating this upcoming October 31 will not be so special because of the boring Halloween celebration due to COVID-19. However, we will have a good reason to look up at the sky: a lunar phenomenon known as Blue Moon will take place.
The Blue Moon will appear on October 31, 2020, and it is characterized that way not because the Moon turns blue, but because it will be the second full moon of the month, as explained in the Farmers’ Almanac.
“For more than half a century, whenever two full Moons appear in a single month (which happens on average every 2 1/2 to 3 years), the second full Moon is christened a Blue Moon,” they explained.
This lunar phenomenon commonly occurs every two and a half to three years, according to the Farmers’ Almanac, but what makes this occasion special is that the event won’t happen again on Halloween for another 19 years, and this pattern is known as the metonic cycle. The last time the Blue Moon was be observed on a Halloween night was in 1944.
The Metonic cycle was discovered in 432 a. C. by the Greek Meton of Athens, who determined that after every 19 years, a lunar phase could repeat itself on the same date, although it has not necessarily happened that way. From 1925 to 1944 the Metonic cycle managed to take place, but since then (between 1963, 1982 and 2001) the cycle changed and moved to November 1. In 2020, the cycle was reassigned to October 31.
“Fun fact: Any time the Moon is technically “full” on October 31st (as it will be this year), it would also have to be a Blue Moon because the lunar cycle is only 29.5 days long, ” they added.
The Blue Moon is expected to reoccur on Halloween in the years 2039, 2058, 2077, and 2096.
