The observers of the sky, the spirits and (especially) the werewolves take into account: The moon will be full tonight on Halloween throughout the United States.
This is a really special fusion of ghostly; Halloween full moon, visible to all time zones on Earth, has not happened since 1944, according to the Agricultural Almanac. This will not happen again until 2039.
But wait, there’s more: The full moon on October 31 is also “Blue Moon, “an indication of the second full moon to occur within a calendar month. Blue moons are also relatively rare, occurring on average only once every about 2.5 years. We last saw one in March 201
Connected: How to observe the moon (infographic)
The current definition of “blue moon” is in fact a misinterpretation of the original, by the way. The term once referred to the third full moon of a season (winter, spring, summer, or fall), which had four full moons instead of the usual three, as defined by the Maine Farmers’ Almanac in the 1930s.
“But in 1946, amateur and often Sky & Telescope astronomer James Hugh Pruet (1886-1955) misinterpreted the Almanac’s description and the second full moon was born in a month.” Sky & Telescope wrote in an explanatory note this week.
And in case you were wondering – the “blue moon” has nothing to do with color. The moon can sometimes appear bluish due to the scattering of light from dust or smoke particles in the Earth’s atmosphere, but such effects are not related to the lunar phases at all.
Halloween Blue Moon
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We can call this full moon on Halloween and the Hunter’s Moon, the traditional name for the first full moon after that. The moon is reaping. The harvesting moon is the one that falls closest to the autumn equinox of the Northern Hemisphere, which occurred this year on September 22. In 2020, this distinction passed to the full moon on October 1.
And one last thing: This year’s Halloween full moon also qualifies as a “micro-moon” or “minimun” because it will appear when the Moon is near its farthest point from Earth in its elliptical orbit. For example, on October 30, the moon will be 406,394 kilometers from us – significantly further from its average distance of about 388,500 km. You probably won’t notice the difference unless you’re particularly sharp or intrusive about such things.
Mike Wall is the author of “Out there“(Grand Central Publishing, 2018; illustrated by Carl Tate), a book on the search for extraterrestrial life. Follow it on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook.