Full Moon Rising on March 31, 2018 in Alberta, Canada (Photo by: VW Pics / Universal Images Group … [+]
Universal Images Group via Getty Images
Next week’s “Cold Moon” is the last 13th full moon of 2020, but it will also be visible on two different days, as the first full moon of a new celestial season and the highest in Earth’s night sky.
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So what’s up with the full “Cold Moon”? ”
What is the cold moon?
It is the full moon of December – also known as the “Long Nights Moon” in North America and, as it occurs just after Christmas Day, the “Moon After Yule” in Europe.
It comes after an amazing “Christmas Star” or “good connection” of planets just before Christmas and a hopeful total solar eclipse, which, of course, was caused by a New Moon sliding perfectly on in front of the sun.
Why is there a ‘Cold Moon’ on two different days?
The Moon reaches 100% illumination at global time 03:29 Universal Time on Wednesday, December 30, 2020. That means that even though Asia Pacific, Europe and Africa will have a full moon on the that date, it happens the day before for both South America and North America – at just 10:29 pm EST and 7:29 pm PST on Tuesday, December 29, 2020.
However, you can find out when to watch for exposure on the eastern horizon by checking out my full guide on when to watch the “Cold Moon” at its best.
The Full Moon appears for about three days on each side.
A full moon rising. (Photo by: Alan Dyer / VWPics / Universal Image Group via Getty Images)
Group VWPics / Universal Images via Getty Images
Why is the ‘Cold Moon’ the Highest in the Earth’s night sky?
The Full Moon of December always rides the highest in the sky. Just a shy 10 days from the solstice, the longest night of the year, the “Cold Moon” takes a higher, more northerly path to the night sky as it faces a low sun. The result is that the Moon will be above the horizon longer than at other times of the year and pass as close to the zenith (the point in the sky just above them) as ever.
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Why are there 13 full moons in 2020?
When we talk about a year we are referring to a tropical year – how long it takes the Earth to orbit the sun. That’s 365 days, 5 hours, 48 minutes and 45 seconds, to be precise.
But the Moon has its own year – a lunar year. It lasts exactly 354 days, 8 hours, 48 minutes, 34 seconds. That’s the time it takes for 12 lunches – a circle of 12 orbits of the Moon around the Earth, each taking 29.53 days. Let’s do the maths: 12 x 29.53 = 354.36 days – lunar year.
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So there is a difference of 11 days which means that a full Moon is “extra” in a calendar year every 2.7 years, on average. Just to make it easy on the Moon, 2020 was also a leap year, with one extra day added on February 29, 2020 to coincide with the calendar year along with the celestial year.
So for a 13th full Moon, the first full Moon of the year must occur within the first 11 days of the year. That’s exactly what happened in 2020, with the “Wolf Moon” turning full on January 10, 2020. So just 354 days later the 13th full moon – the “Cold Moon” – comes in .
Full moon revolution in March 2020. (Photo by: Alan Dyer / VW PICS / Universal Images Group via … [+]
Group VW Pics / Universal Images via Getty Images
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What do we call this 13th ‘extra’ full moon?
That was noticed in October 2020 when there were two full moons in one month – an inevitable result of 13 full Moons in one year, of course.
The second full moon in a calendar with two full moons is referred to as a “monthly blue moon”. “Once in a Blue Moon.” In 2020 that happened on Halloween, but that was called “Hunter’s Moon” according to what has always been October.
The “Autumn Moon” traditionally describes the Full Moon closest to the equinox on September 22, 2020, but the Full Moon fell closest to October 1, 2020. With the “Harvest Moon” in the September turned into October, the full Moon of September was like an unnamed moon. It became the “Corn Moon” – a name reserved for such times – leaving the rest of the full Moons 2020 to use their usual names.
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Why is the ‘Cold Moon’ like the first full moon of a new celestial season?
Astronomical seasons begin and end on solstices and equinoxes. Since the December solstice on 21 December 2020, that is when the winter season began. So while the “Cold Moon” may seem like it belongs to 2020, it is in some ways starting until 2021.
The next full moon is the “Wolf Moon” – known as the “Snow Moon” and the “Ice Moon” – and will take place on Thursday, January 28, 2021.
Wishing you clear skies and wide eyes