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Between October 31 and November 1 it is possible to observe the so-called “blue moon” or “blue moon”. A term, which does not refer to the color of the natural satellite, coined to define an astronomical phenomenon which indicates that there will be two full moons in the same month.
According to NASA scientists, the particular event occurs – approximately – every two and a half years. In fact, the last time it was possible to see it was on March 31, 2018, and it won’t be repeated until 2023.
“Normally the months have only one full moon, but eventually there may be a second. The full moons are separated by 29 days, while most of the months last 30 or 31 days, so it is possible to identify two full moons in the same month “, explain the US space agency.
In 2020 we add the particularity that the phenomenon will take place during the Halloween celebrations and in advance of the Day of the Dead, a traditional ceremony in Mexico.
What is the origin of the term of that moon?
The reference to the astronomical phenomenon emerged in the 1940s, when the magazine Sky & Telescope published an article in 1946 entitled “Once every Blue Moon”. The author, James Hugh Pruett (1886-1955) miscalculated according to a 1937 almanac and said: “The second (Full Moon) in a month, as I interpret it, is called the Blue Moon.” It was a mistake, but the nickname has remained in popular culture forever.
However, NASA also explains that “very rarely” can “blue colored moons” occur, due to the presence of certain particles caused by natural disasters. “In 1883, an Indonesian volcano called Krakatoa exploded so badly that scientists likened it to a 100 megaton nuclear bomb. Much ash from the Krakatoa explosion has gone up into the atmosphere. “The ash particles were about 1 micron in size, so they could scatter red light and act as a blue filter.
As a result, in the years following the Krakatoa explosion, the moon was blue. Similarly, the BBC explained that there were also reports of blue moons in Mexico in 1983, after the eruption of El Chichón volcano, and in Washington state in 1980, after the eruption of Mount Santa Helena.
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