One7 - The Winter solstice , which takes place today, marks the shortest day and the longest night of 2018. Here's all you need to know. Today , December 21, marks the Winter solstice the first day of winter in the northern hemisphere — the shortest day and the longest night of the year. It happens once a year in every hemisphere and perhaps the reason why this day is so unique. This is the day when Sun appears at its most southern position. The solstice this year is also special because it will be followed the next day by a full moon, called the Cold Moon , which will be visible in the night with the Ursid meteor shower. Here’s all you need to know about the Winter solstice, how long is it, and its relevance What does solstice mean? The term ‘solstice’ is derived from two Latin words “sol” which means sun, and “sistere”, meaning standstill. The Sun seems to stand still in the winter sky, marking the shortest day and longest night of the year.