The Winter Solstice
"In the bleak mid-winter
Frosty wind made moan;
Earth stood hard as iron,
Water like a stone."
~ In the Bleak Midwinter, Christina Rossetti (1830-1894)
Today marks the longest night and the shortest day of the Northern Hemisphere, long viewed by ancient cultures as a time of death and rebirth. The actual date of the winter solstice varies from year to year, and can fall anywhere between December 20 and December 23, with the 21st or 22nd being the most common. The term 'solstice' derives from the Latin word 'solstitium', meaning 'Sun standing still'. On this day the Sun seems to stand still at the Tropic of Capricorn and then reverses its direction as it reaches its southernmost position as seen from the Earth. Stonehenge, the prehistoric monument located in Wiltshire (c. 2500 BCE) , is carefully aligned on a sight-line that points to the winter solstice sunset (opposed to New Grange, which points to the winter solstice sunrise, and the Goseck circle, which is aligned to both the sunset and sunrise). The only other megalithic monuments in the British Isles which clearly align with the sun are Newgrange in County Meath, Ireland and Maeshowe situated on Mainland, Orkney, Scotland. Both famously face the winter solstice sunrise. Today modern astronomers, such as those at The Scottish Dark Sky Observatory near Loch Doon, East Ayrshire, Scotland, with its low levels of light pollution and clear horizon views, contemplate the mysteries of the universe year round.
The winter solstice (or hibernal solstice), also known as Midwinter, Yule, the Longest Night, Jólis, and other names is an astronomical phenomenon marking the day with the shortest period of daylight and the longest night of the year. In the Northern Hemisphere this is the December solstice and in the Southern Hemisphere this is the June solstice.
More evident from high latitudes, a hemisphere's winter solstice occurs on the day with the shortest period of daylight and longest night of the year, when the sun's daily maximum elevation in the sky is at its lowest. Although the winter solstice itself lasts only a moment in time, the term sometimes refers to the day on which it occurs.
This tartan was designed for the Dark Sky Observatory in Dalmellington, Ayrshire, Scotland, using colours that reflect the night sky.
In astrophysics and physical cosmology, Olbers' paradox, named after the German astronomer Heinrich Wilhelm Olbers (1758–1840), also known as the "dark night sky paradox", is the argument that the darkness of the night sky conflicts with the assumption of an infinite and eternal static universe. The darkness of the night sky is one of the pieces of evidence for a dynamic universe, such as the Big Bang model. In the hypothetical case that the universe is static, homogeneous at a large scale, and populated by an infinite number of stars, then any line of sight from Earth must end at the (very bright) surface of a star and hence the night sky should be completely illuminated and very bright. This contradicts the observed darkness and non-uniformity of the night.
The Scottish Dark Sky Observatory occupies a hilltop site on the edge of the Galloway Forest Dark Sky Park. This publically accessible educational observatory has some of the darkest skies in the UK and two large telescopes through which to observe the night sky.
To learn more about the Dark Sky Paradox, click the Dalmellington Dark Sky Observatory.