Google's winter solstice 2017 animation. This year, that moment will occur at 16:28 Coordinated Universal Time (UTC). The winter solstice occurs Thursday at 11:28 a.m. On the December solstice, the sun's daily southward movement in the sky appears to pause, and we see the sun rise and set at its southernmost points on the horizon before reversing direction.
The date where Earth is the nearest to the star is marked by the summer solstice.
While a solstice represents either a longest or shortest day, the equinox falls on the days where day and night are the same length.
The winter solstice is marked by the point at which the North Pole is at its farthest from the sun during its yearly orbit around the sun. "The extra 30 seconds of a solar day makes true solar noon - and sunrise and sunset - about 30 seconds later each day".
The astronomical seasons are based on the position of the Earth in relation to the Sun.
For more than 4,000 years, Stonehenge has stood like a Neolithic sundial, marking the longest day of the year and the shortest - taking aim at the sun like a giant stone gunsight.
IT feels like the nights have been drawing in forever, but from now the days start to get longer again. Eastern on December 21.
On the 21st the Sun pauses in this the longest night of the year.
This happens twice a year, mid-way between the summer and winter solstices, on March 21 and September 23.
The organisers of the event write on their website: "The Winter Solstice is the most important day of the year at Stonehenge and a truly magical time to be there".
In the Lower 48, the sun is up for more than 10 hours across Florida and southern Texas, while states across the northern tier get under nine hours of daylight.
You would think our temperatures will be at the coldest on the Winter Equinox but the truth is that there is a lag time in the cold.
You may have noticed two special lines of latitude on a globe of the world: One in the Northern Hemisphere called the Tropic of Cancer at +23.5° latitude and one in the Southern Hemisphere called the Tropic of Capricorn at - 23.5° latitude.