Above: Manish Mamtani captured the full Cold Moon over Maine’s Nubble Lighthouse, which was lit up for the holiday season in 2019. Many called this full moon the last of the decade. View at EarthSky Community Photos.
To many, the last full moon of the decade came last year, on December 12, 2019. But purists will call the December 2020 full moon the last full moon of the decade. It happens on December 29 or 30, depending on your time zone (more full for the Americas on the night of December 29; round and full on December 30, too, for everywhere worldwide). Like every full moon, December’s full moon has its own special characteristics. And like every full moon, it carries a name. At northerly latitudes, we call the December full moon the Cold Moon or Long Night Moon. It shines in the sky from dusk to dawn, like a wonderful nocturnal sun, giving us a much-appreciated reprieve in the season of diminished daylight.