Dec. 23, 2:51 a.m. EST - The Full Cold Moon: among some tribes, the Full Long Nights Moon. In this month the winter cold fastens its grip, and the nights are at their longest and darkest. Also sometimes called the "Moon before Yule" (Yule is Christmas, and this time the Moon is only just before it). The term Long Night Moon is a doubly appropriate name because the midwinter night is indeed long and the Moon is above the horizon a long time. The midwinter full Moon takes a high trajectory across the sky because it is opposite to the low Sun.