Blog: The Solstices
Date: 6 November 2019Copyright © David Boettcher 2006 - 2020 all rights reserved.
The solstices are notable events in the solar calendar. Here I explain what the word solstice means, and why the winter solstice has been a source of both dread and celebration for many thousands of years.
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The two solstices are notable events in the solar calendar. They are known as the shortest and longest days of the year, and the winter solstice, the shortest day with the smallest number of hours of hours of daylight, has been celebrated for millennia - for good reason!
The two solstices occur around 21 June and 21 December each year.
The word solstice comes from the Latin words sol for sun and stit meaning stop or stand, which has the same Latin root as the stet that editors write when they change their mind and want some text that they have deleted to remain. The Latin solstitium became the English solstice, which literally means that the sun stops.
On the solstices the sun doesn't stop or stand still in space; the solstices are the limits of the progression through the year of the position of sunrise and sunset along the eastern and western horizons. If you watch where the sun rises on the eastern horizon, or sets on the western horizon, throughout the year, you will notice that in the winter it rises and sets further to the south than it does in the summer, and that as the seasons change the position of sunrise and sunset gradually cycles between two extremes. The position of sun rise and sun set appears to march along the horizon from midsummer to mid winter. When it gets to a solstice, the position of sunrise and sunset stops marching in one direction, appears to stand still for, and then starts marching in the other direction.
The figure here is a sketch of where the sun rises on the eastern horizon at each solstice. From its rise furthest to the left or north on midsummer's day, the point at which it rises gradually moves to the right on the horizon, towards the south, as the year moves on towards winter. The further south that it rises, the lower it is at its zenith in the sky at mid day, and the shorter and colder the days are. The same thing happens at sunset; as winter draws on the sun sets gradually further south on the western horizon.
It is easy to image an early human watching this happening and becoming worried. As sunrise and sunset move along the horizon and the days get shorter and colder, without any knowledge of celestial mechanics and how the earth moves around the sun, they would worry that eventually the sun might not rise and the earth would be plunged into freezing darkness. Which of course is what does happen inside the Arctic circle . . .
But assuming that our early human is watching this from somewhere south of the Arctic circle, one day the sun would stop rising and setting further south on the horizon. It pauses, and then starts rising and setting further north. What a huge relief that would have been! The days would gradually start to lengthen and warmth would return. In time spring would come; grass and crops would start to grow again, and trees would put on leaves.
The day on which the sunrise and sunset stop marching south on the horizons and start marching north is called the day on which the sun stands still: the solstice. And knowing that the sun has stopped marching south, has turned round, and is marching north towards longer and warmer days is a great reason to celebrate! Happy solstice!
Copyright © David Boettcher 2006 - 2020 all rights reserved. This page updated December 2019. W3CMVS.