Why this week’s “cold Christmas moon” is the 13th, last and highest full moon of the year

Next week’s full “Cold Moon” will be the 13th and final full moon of 2020, but it will also be visible on two separate days, will be the first full moon of a new astronomical season, and the highest in Earth’s night sky .

So what happens with the full “Cold Moon?” ”

What is the “Cold Moon? ”

It is the December Full Moon, also known as the “Long Night Moon” in North America and, since it occurs just after Christmas Day, the “After Christmas Moon” in Europe.

It comes as a result of a spectacular ” Christmas star “ Where “Great conjunction” of planets just before Christmas and an impressive total solar eclipse this, of course, was caused by a New Moon sliding perfectly past the Sun.

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Why is there a “cold moon” on two different days?

The Moon reaches 100% illumination at 3:29 am World Time Universal Time on Wednesday, December 30, 2020. This means that if Asia-Pacific, Europe and Africa will have a Full Moon on this date, it will be actually produced the day before for both South America and North America, at 10:29 p.m. EST and 7:29 p.m. PST on Tuesday, December 29, 2020.

However, you can find out exactly when to watch it appear on your eastern horizon by checking out my exhaustive guide at when to watch the “Cold Moon” at its best.

The Moon will appear full for about three days on each side.

Why is the “Cold Moon” the tallest in Earth’s night sky?

The December full moon rises ever higher in the sky. Just under 10 days before the solstice, the longest night of the year, the “Cold Moon” will take a higher and more northerly course across the night sky as it is opposite a low sun. The result is that the Moon will be above the horizon longer than at other times of the year and will pass as close to the zenith (the point in the sky directly above) as ever.

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. It is 365 days, 5 hours, 48 ​​minutes and 45 seconds, to be precise.

However, the Moon has its own year, a lunar year. It lasts precisely 354 days, 8 hours, 48 ​​minutes, 34 seconds. This is the time it takes for 12 lunations, a cycle of 12 orbits of the Moon around the Earth, each taking 29.53 days. Let’s do the math: 12 x 29.53 = 354.36 days, a lunar year.

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So there is an 11-day gap which means that every 2.7 years, on average, there is an “extra” Full Moon in a calendar year. Just to make things easier on the Moon, 2020 was also a leap year, with an additional day added on February 29, 2020 to keep the calendar year in sync with the astronomical year.

So, for there to be a 13th full moon, the first full moon of the year must occur within the first 11 days of the year. This is exactly what happened in 2020, with the “Wolf Moon” becoming full on January 10, 2020. So, exactly 354 days later, the 13th full moon – the “Cold Moon” – occurs.

What do we call this 13th “extra” full moon?

This was settled in October 2020 when there were two full moons in a month – an inevitable consequence of having 13 full moons in a year, of course.

The second full moon of a calendar month that contains two full moons is called a “monthly blue moon”, as in the saying “once in a blue moon.” In 2020 that happened on halloween, but it has been called a “hunter’s moon” in accordance with what are always called the full moons of October.

The “Harvest Moon” traditionally describes the full moon closest to the equinox of September 22, 2020, but the closest full moon fell on October 1, 2020. With the September “harvest moon” moved to October, the September full moon was a moon without a Name. It has become the “corn moon”– a name reserved for such occasions – leaving the rest of the Full Moons of 2020 to use their usual names.

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Why is the “Cold Moon” the first full moon of a new astronomical season?

Astronomical seasons begin and end at the solstices and equinoxes. Since the December solstice took place on December 21, 2020, this is when the winter season began. So while it may seem like the “Cold Moon” belongs to 2020, it actually begins in 2021.

The next full moon will be the “Wolf Moon” – also known as the “Snow Moon” and “Ice Moon” – and it will take place on Thursday, January 28, 2021.

I wish you a clear sky and big eyes

Troy M. Hoffman