The truth behind the Halloween 2020 blue moon, according to an Astronomer
October of 2020 is an exicting month for the moon, with a full moon on the first day of the month, and the last day of the month, making the full moon on October 31st 2020, a blue moon.
“In this case, the moon’s cycle is under 30 days, because of that you can have an event that you get more than one full moon in a given month,” Jackie Faherty, an astronomer at the American Museum of Natural History in New York City, tells Yahoo Life. “The second full moon of any given month, we refer to as a ‘blue moon’.”
This full moon will not actually be blue, however Faherty says that there are occasions where the moon can appear in hues of orange or blue, due to an effect caused by the Earth’s atmosphere. “It changes color as it passes through the most amount of atmosphere, it can create these gorgeous colors for you,” she says. “So it will look orange, it can even look blueish.”
According to Faherty, however, a blue moon occurs about every two to three years, which she doesn't consider a very rare occurance. She says a more accurate rare phenomena to reference would be a Milky Way supernova, when a star explodes in our galaxy, which happens approximately every 50 years. A “very very rare” occurrence according to Faherty.
None the less, Faherty says any full moon can be spectacular to watch, and she recommends trying to watch the moonrise as well if you can. “Everybody gets all romantic about the sunrise and the sunset but a moonrise and a moonset can be very dramatic and exciting,” Faherty tells Yahoo Lifestyle. “They are spectacular.”
Video Transcript
JACKIE FAHERTY: In October of 2020, we will have two full moons-- at the very beginning of the month, and at the very end of the month. And in this case, the moon's cycle is under 30 days. Because of that, you can have an event that you get more than one full moon in a given month. And the second full moon of any given month we refer to as a Blue Moon.
Now, the expression, as it goes, is "once in a blue moon." That seems like something that shouldn't happen a lot. But it's not really the case for blue moons. You get a blue moon every two-ish years or so.
I don't like to call things that can happen many times over my lifetime a rare event, so my preference is for something that's maybe going to happen once if not maybe ever in my lifetime. Rather than once in a blue moon, you might note something that really does happen very rarely. And in the Milky Way, that would be having a supernova going off-- so when a star explodes in our own galaxy and gets so bright that it even rivals the moon. And I would say then "once in a Milky Way supernova" would be the expression that we should swap out for "once in a blue moon."
