Today, the Northern Hemisphere will be tilted as far away from the sun as it will be all year. It’ the first day of winter, it’s also the shortest day — and longest night — of the year. This year’s winter solstice occurs at exactly 11:48 p.m., Eastern Time. In astronomy, the solstice occurs at the moment the earth's tilt away from the sun is at a maximum. On the day of the winter solstice, the sun appears at its lowest elevation with a noontime position that changes very little for several days before and after the winter solstice.