The turning of the light
At the December solstice the Sun is directly overhead along the Tropic of Capricorn, and the northern hemisphere is tilted as far from it as it ever gets. The Sun's noon path is lowest and the day is shortest. Beyond the Arctic Circle it does not rise at all, while south of the Antarctic Circle it never sets.
After this moment the northern days begin lengthening again, slowly at first. That is why so many winter festivals are really celebrations of returning light.
Winter in one half, summer in the other
In northern countries, the solstice brings the longest night. In Brazil, Argentina, Chile, South Africa and Australia it is the first day of summer, with the most daylight of the year, which is why Christmas there often means beaches and barbecues.
Meteorologists open winter on 1 December, a clean month boundary, while astronomers wait for the solstice. Remember that Earth is nearest the Sun in early January, so northern winter happens when we are closest to it; the tilt, not the distance, rules.
Midwinter customs
- Yule. Northern European tradition celebrated the return of the Sun with fires, evergreens and feasts, and many of those customs live on in the Christmas season.
- Dongzhi. In China and across East Asia families gather for the Winter Solstice Festival, eating tangyuan rice balls or dumplings.
- Stonehenge. The monument also frames the winter solstice sunset, and visitors gather there.
- Astrology. By tradition the Sun enters Capricorn, the sign of structure and patience.
Making the most of the day
In the north, many people mark it by lighting candles, going for a walk at sunset or simply noting that the dark has peaked. In the south, long evenings invite outdoor gatherings. The sky also gives northern observers a high, bright winter Moon, because the Full Moon sits opposite the Sun and so rides high when the Sun is low; see the Moon phases hub for the current phase.
The cycle then returns to the March equinox. You can see all four turning points together on the equinoxes and solstices hub.
Questions people ask
Is the shortest day also the day of the earliest sunset?
Not exactly. The earliest sunset comes a week or two before the solstice and the latest sunrise a week or two after it, because of the equation of time, the uneven pace of the Sun's apparent motion through the year.
Is the December solstice summer in Australia?
Yes. In Australia, Brazil, Argentina and Chile it starts summer and is the longest day of the year.
Why does the coldest weather come later?
Land and oceans lose heat slowly, so the lowest temperatures usually arrive some weeks after the solstice in the north.