21 years: 2005 - 2026

Blog: The Solstices

Copyright © David Boettcher 2005 - 2026 all rights reserved.

First published: 6 November 2019, last updated 21 December 2025.

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 Solstices

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!

There are two ways to look at the solstices. The popular way is that they are the days with the greatest and least number of daylight hours. The other way is that they occur at the precise moment when the Earth’s tilted axis points most directly towards or away from the Sun. Astronomically, a solstice is the instant when the Sun’s apparent position reaches its northernmost or southernmost point in the sky, which means the astronomical solstice occurs at a precise time rather than being a calendar day.

The two solstices occur around 21 June and 21 December each year. In the northern hemisphere these are the summer and winter solstices respectively, in the southern hemisphere they are the other way round.

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 or stands still.

On the solstices the Sun doesn't actually stop or stand still in space; it stands still on the horizon, that is it stops moving place along the horizon at sunrise and sunset. The solstices occur at 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 figure here is a sketch of where the Sun rises on the eastern horizon at each solstice. The position of sunrise and sunset 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.

Winter Solstice

The winter solstice is by far the more important, because it marks the point at which the days stop getting shorter and start to lengthen again, promising the end of winter and the arrival of spring. On a technical note, of course a day remains 24 hours long, the length of the day refers to the number of daylight hours.

The summer solstice is less noticeable, because the days are long and the Sun rises before most people wake, and sets after they have gone to sleep, and a few minutes more or less of daylight doesn't seem important. But at the winter solstice, the days are short, it's dark when people rise, and dark long before they go to bed, so every moment of daylight is precious.

From its point of rising furthest to the left or north on the eastern horizon on midsummer's day, the point at which the Sun rises gradually moves to the right or south on the horizon as the seasons moves on towards winter. The further south that the Sun 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 on the western horizon gradually further south.

It is easy to image an early human watching this happening and becoming worried. As sunrise and sunset move along the horizons to the south 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 descend into permanent freezing darkness. Which of course is pretty much 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!

Summer Solstice

In the northern hemisphere, as spring turns into summer, you might have noticed that the Sun rises on the eastern horizon further to the north. This means that if you note the point at which the Sun rises, it gradually moves left from your perspective as the days get longer. When the point at which the Sun rises stops moving to the north, or to your left, that is the summer solstice.

The summer solstice gives the day with the greatest number of daylight hours, for which reason it is called the longest day, although of course it remains 24 hours long in total; the longest day really means the day with the greatest number of daylight hours.

The summer solstice is sometimes called midsummer day, although it occurs at what is generally reckoned to be near to the start of summer. In Britain, July and August are usually the hottest months of the year. June is frequently disappointing as prevailing westerly winds, which are often absent in April and May, bring warmer but wetter air in from the Atlantic.

The summer solstice marks the day from which the days begin to get shorter, and then cooler as autumn and winter approaches. In the northern hemisphere it occurs on or around 21 June. But there is usually plenty of summer to come - enjoy it while it's here!

Sunrise and Sunset around the Solstice

The graph here shows how the times of sunrise and sunset vary around the solstice. The data plotted on the y axis are the difference between the times of sunrise and sunset at the solstice and their times at the date on the x axis. The times vary by location, this data is for a location near to Macclesfield in Cheshire.

The red and blue curves show that although the solstice is the shortest day, the latest time of sunrise and the earliest time of sunset don't occur on the solstice.

The earliest sunset occurs before before the solstice, on about 14 December, when the Sun sets about two minutes earlier than it does at the solstice. The latest sunrise occurs after the solstice on about 30 December, when it is about two minutes later than it is at the solstice.

This shows that even before the solstice, the sunset is getting later, making evenings shorter. However, because the time of sunrise continues to get later, the length of the day continues to shorten until the solstice. After the solstice, it doesn't start getting light earlier in the morning until January.

However, despite these details, the solstice is still the day when the Sun stops moving southwards on the eastern and western horizons and starts moving northwards.

Technically, the solstice is when the Sun’s declination (its north–south angular position in the sky) reaches its most southerly value. At that instant the Sun stops moving southward in the sky from day to day and begins moving northward again. That corresponds to the Sun rising and setting at the furthest south positions on the east and west horizons. On the day of the solstice, the Sun stands still, and afterwards those horizon points start moving north again.

Flaming June?

With the arrival of June comes frequently wet, showery and often thundery weather. What happened to “Flaming June”, an often-heard phrase that seems to promise that there should be scorching sunshine for the month of June.

Flaming June is actually the name of an 1895 painting by Lord Frederic Leighton, not a statement about the weather for the month of June, which is often not flaming - sometimes far from it.

The arrival in Britain of wet weather in June after a spell of dry weather in the spring is due to a meteorological phenomenon known as the “return of the westerlies”, or sometimes even the “European monsoon.” In the spring, clear blue skies, dry weather and cold nights are due to dry easterly winds, which are dry because they don't cross an ocean. The North Sea is actually very small and shallow compared to the Atlantic ocean, so it can store very little heat and winds from the east don't pick up much heat or moisture as they cross it.

Around June the wind switches back to more normal westerly winds. These blow across the Atlantic ocean, which is not only vast in area, it is also very deep, which means it can store a lot of heat during the summer months. Westerly winds pick up a lot of heat and moisture as they cross it, bringing warm damp air to Europe, which turns to clouds and rain. The westerlies keep Europe warmer in the winter than it would otherwise be, but also wetter whenever they blow, which is often in June.

Earth's Distance From The Sun

Johannes Kepler was probably the first person to realise that the earth's orbit around the Sun is elliptical rather than circular, with the Sun at one of the foci of the ellipse.

The earth's greatest distance from the Sun is just over 94.5 million miles at a point called the aphelion, from the Greek apo, meaning away, and helios for the Sun. The aphelion occurs during the northern hemisphere's summer, a few weeks after the summer solstice.

The earth's least distance from the Sun is just over 91.4 million miles at a point called the perihelion. Unfortunately this is rather un-memorably from the Greek peri, meaning around, and helios for the Sun. Using the inverse square law, solar radiation at the earth at perihelion is about (94.5/91.4)² = 1.069, or nearly 7%, more intense than it is at aphelion.

The earth's orbital speed is fastest when it is at perihelion and slowest at aphelion, meaning that the northern hemisphere summer is slightly longer than the southern.