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In January, we promised our readers that 2020 would be a stargazer’s treat, especially when it came to full Moons. In total, for 2020, we’ll have 13 full Moons, including 2 two Supermoons, and a rare Halloween Blue Hunter’s Moon on October 31st. It’s rarer in more ways than you may realize!
What is a Blue Hunter's Moon?
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.”
When you look at the full Moon on Halloween night, it won’t appear blue in color but you’ll be looking at something pretty uncommon. A full Moon on Halloween occurs roughly once every 19 years—a pattern known as the Metonic Cycle.
This well-known lunar cycle was discovered in 432 BC by the Greek, Meton, of Athens. He determined that after 19 years have elapsed, the phase of the Moon will repeat on the same date.Well . . . not always. Because of slight variations in the Moon’s orbital period, and the number of leap days that intervene over a 19-year time span, the Metonic Cycle can be accurate only to within a day.
For a Halloween full Moon, the Metonic Cycle worked well early in the 20th Century—in the years 1925 and 1944. But thereafter, using the cycle, the date of full Moon shifted a day to November 1st (in 1963, 1982, and 2001). But then, in 2020, it returned to October 31st. Making it a rarer sight, indeed.
What is a Blue Hunter's Moon?
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.”
When you look at the full Moon on Halloween night, it won’t appear blue in color but you’ll be looking at something pretty uncommon. A full Moon on Halloween occurs roughly once every 19 years—a pattern known as the Metonic Cycle.
This well-known lunar cycle was discovered in 432 BC by the Greek, Meton, of Athens. He determined that after 19 years have elapsed, the phase of the Moon will repeat on the same date.Well . . . not always. Because of slight variations in the Moon’s orbital period, and the number of leap days that intervene over a 19-year time span, the Metonic Cycle can be accurate only to within a day.
For a Halloween full Moon, the Metonic Cycle worked well early in the 20th Century—in the years 1925 and 1944. But thereafter, using the cycle, the date of full Moon shifted a day to November 1st (in 1963, 1982, and 2001). But then, in 2020, it returned to October 31st. Making it a rarer sight, indeed.
A Rare Halloween Blue Moon in 2020 - Mark Your Calendars!
We'll be treated to a rare Halloween full Blue Hunter's Moon. Why is it so rare, and when will we see the next one? We explain.
www.farmersalmanac.com
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