This special phenomenon is also called a full moon or long night moon.
This text is a translation of an article from CTV News.
According to the Old Farmer's Almanac, an almanac containing weather forecasts, astronomical data and more, a full Christmas moon typically occurs about every 19 years. The last case occurred in 2015 and after December this year it is expected to occur again in 2034.
This will be the first full moon after the winter solstice, which occurred on December 21 in the Northern Hemisphere and marks the first day of winter, or the shortest day of the year.
It is also the 13th and last full moon of the year, says The Old Farmer's Almanac online.
The Old Farmer's Almanac states: “To our eyes the disk of the moon appears fully illuminated a few days before the full moon. So on December 24th and 25th, look east after sunset as the moon rises on the horizon.”
According to The Old Farmer's Almanac and NASA, the full moon will rise just before sunset on December 25-27 and will appear high and full on Christmas Day. The full moon is expected to be fully illuminated at 7:33 p.m. Eastern Time on December 26th.
If you look east after sunset on December 24th and 25th, you will see the moon rise and its disk appear fully illuminated before the full moon.
The Old Farmer's Almanac has a moonrise calculator that shows the exact time it will appear in your area.
The cold moon is expected to reach maximum brightness in Toronto on December 26, rising in the northeast at 4:09 p.m. and setting in the northwest at 7:55 a.m. In Fredericton, maximum brightness is expected to occur this day, rising in the northeast at 4:04 p.m. and setting in the northwest at 8:13 a.m.
The full moon in December appears to touch the top of the sky. During the winter solstice, it stays above the horizon longer than any other moon, which explains why it is the longest night.
The full moon in December is commonly referred to as the cold moon, a Mohawk name that refers to the cold conditions of this time of year.
Its other name, “Long Night Moon,” is a Mohican term that refers to the moon that rises on the “longest nights” of the year.
Native Americans traditionally used the monthly moons and signs of nature as a calendar to track the seasons, explains The Old Farmer's Almanac.
Europeans now call it the pre-Christmas moon, referring to an ancient northern European winter holiday associated with Christmas, NASA notes.