It happens every year. Whilst we’ve all got our attention turned towards Christmas, the Winter Solstice sneaks in under the radar and gives us another annual gift. Between 21st and 22nd December, up here in the Northern Hemisphere we experience our shortest day.
But what on earth is the Winter Solstice? What are the physics behind shorter days and longer nights? And who celebrates it? If you’re intrigued, and need a break from the Christmas slog, read on…
It’s the winter solstice today, which means just 8 hours of daylight and the shortest day of the year. The good news is that from here on to the midpoint of summer – daylight hours are getting longer again. Yup, in just 6 months time, you’ll be treated to 16 daylight hours every 24 hrs.
The Winter Solstice is the name given to the point at which daylight hours are shortest, where several aspects of geophysics conspire to make it happen. Here’s the science bit…
1. The Earth does a complete Orbit around the sun over one year (or if we’re being pedantic every 365.25 days – hence the 1 in 4 leap year to make up the 0.25 loose end). That orbit is elliptical, not circular – so it spends about three months at each end of the parabolic loop.
2. The earth takes 24hrs to revolve, during which time it spins to face the sun (sunrise as it rotates into the sun, sunset as it spins away) giving us our daylight hours.
3. The Earth’s axis is tilted – which means that as it goes round the sun on its orbit trajectory the amount of light hitting different halves of the planet (northern and southern hemispheres) changes. During winter (when the Earth is at one end of its orbit round the sun) in the Northern Hemisphere the amount of light is less due to the angle of our part of the planet. Conversely it is greater in summer – at the other end of the annual elliptical orbit.
If that’s hard to follow – the graphic on the right might shed a tad more light on it (groan).
Festivals and Celebrations
Long before most religions had been invented, people worshipped the sun and seasons. And whilst those ancient civilisations didn’t have the benefit of scientific instruments to fully understand the physics, they knew something significant was afoot in the universe. Pagans, Druids and Romans all worshipped the sun, whilst the Norsemen regarded our star as a wheel that turned the seasons – and it’s widely believed that their word for wheel – howl – gradually morphed into Yule. The Romans celebrated Saturnalia (the rebirth of the year) for 7 days from 17th December, whilst Druids began the tradition of the yule log.
Do it yourself
If that’s whetted your appetite and you’re feeling the urge to celebrate the solstice in some way, then there is a ritual that you can adopt. Have a look here over on The Celtic Connection for the Yule Ritual.
If you’re feeling depressed or sad – there’s very little scientific evidence to suggest that it’s to do with winter and the lack of sunlight. Whilst some scientists believe that the lack of sunlight makes your brain to convert the body’s stores of seratonin to melatonin (making you sleepy) demographic data doesn’t imply higher instances of sadness in baltic countries such as Greenland or Norway. In fact neighbouring Denmark is regarded as the happiest country in the world.