Peak of the full moon occurs at 12:45 p.m. Saturday, and it will rise in the eastern sky shortly after sunset. It’s a 5:04 p.m. rise, if you’re watching from here in Washington. Clouds are likely to be minimal locally, although much of the Lower 48 may be dealing with cloud cover Saturday night.
The cold full moon is an extra treat this year because of its proximity to the winter solstice, which occurs the day before, on Dec. 21. Per EarthSky, “The last time the December solstice and full moon happened less than a day apart was in 2010, and the next time will be 2029.”
Thanks to this overlap, the Northern Hemisphere’s longest nights will be strongly illuminated, at least in places where a lack of clouds offers such a prize.
This year’s Cold Moon will also be brighter than normal. This is because the full Cold Moon is coming during perigee. Perigee is when the moon is at or near its closest approach to Earth. When the moon is far off, it is in apogee. Perigee also causes higher-than-usual tides, which are ongoing and anticipated in the days ahead.
Perigee and apogee occur because the moon’s orbit is elliptical, rather than circular. The elliptical shape allows for changes in speed of the moon’s orbit and also its relative size in our sky.
Since this is a full moon in perigee, some are calling it a supermoon. In this case, there is disagreement among primary sources for supermoon status, as further detailed in a post on the subject.
The short story here is that this Cold Moon fits the general idea of a supermoon, which has led some experts to conclude it is one. But, the definition is somewhat ambiguous and also difficult to quantify perfectly. Other sources do not list it as a supermoon.
Whether or not it’s a supermoon, the Cold Moon promises to offer extra light at a time when we could use it most across our part of the planet. Don’t forget to look up!