On October 31, a Blue Moon will light up the skies as people begin to celebrate the pagan holiday of Halloween. It is a rare phenomenon, with a Blue Moon taking place on Halloween an average of every 19 years.
Despite what the name suggests, the Blue Moon will not actually be blue.
The lunar satellite will remain white, but gets its name because it is the second full Moon of the month, the the Harvest Moon occurring on October 1.
According to NASA, the term Blue Moon has volcanic roots.
The space agency said: “The term Blue Moon is believed to have originated in 1883 after the eruption of Krakatoa.
“The volcano put so much dust in the atmosphere that the Moon actually looked blue in colour.
“This was so unusual that the term ‘once in a Blue Moon’ was coined. However, Blue Moon was also used in much the same way we use the term ‘Harvest Moon’.”
The upcoming Full Moon is what is known as Hunter’s Moon, a name given by native American’s who used it as a signal to go hunting in preparation for the impending winter.
According to Time & Date, the Hunter’s Moon will rise at 16.53 GMT.
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“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.”