The winter solstice is a key point in the astronomical calendar and marks the change from autumn to winter.
Astronomical seasons are based on the position of the Earth in relation to the Sun.
The Earth’s axis is tilted at an average of 23.5 degrees. As the Earth travels on its year-long path around the Sun it is tilted towards or away from the Sun, which gives us our seasons.
When the North Pole is tilted towards the Sun, it is summer in the northern hemisphere.
In December, the winter solstice marks the exact moment the northern hemisphere is tilted the furthest away from the Sun. This is the shortest day of the year with the fewest hours of daylight.
The exact moment of the winter solstice varies from year to year due to a slight misalignment between the Gregorian calendar and the actual rate of the Earth’s rotation around the Sun, but it usually falls on 21 or 22 December.
