As the southern hemisphere celebrates the start of summer, those north of the equator will experience the shortest day of the year, known as the winter solstice. This year, it falls on 21 December.
The word “solstice” derives from sol, the Latin word for sun, and sistere, which means “to come to a stop or make stand”.
Arriving on the same day across the globe, a solstice occurs when the sun reaches its lowest or highest point in the sky during the year as a result of the Earth’s axis tilting to or away from the sun.
Historically, the winter solstice has been of great importance to many cultures, such as Ancient Egypt and Ancient Rome, often as a marker for the passing seasons, and a possible time of rebirth.
In northern Europe, from the Faroe Islands to Estonia, Germanic peoples have long celebrated the event, which became known as Yule.
According to Pliny the Elder, in Britain, druid priests would mark the important date by gathering mistletoe and sacrificing bulls – which was also likely a practical measure to limit the number of mouths to feed during months of famine.
In addition to mistletoe and 12 days of festivities, several Christmas traditions, such as Yule logs and decorating trees, date back to Yule, which were later adopted and adapted by Christians.
But the winter solstice is still celebrated in parts of the UK and US. The most popular annual tradition sees druids, pagans and enthusiasts gather at Stonehenge to watch the sun rise.