The winter solstice is an astronomical phenomenon that occurs every year during winter in the Northern Hemisphere. It is the time when the Earth’s north pole is maximally tilted away from the sun, resulting in the shortest day and longest night of the year.
The winter solstice usually occurs on December 21-22 each year and marks the beginning of winter in the Northern Hemisphere. The temperature may get colder in most northern regions but after this date the days also gradually start to lengthen again.
The Arctic Circle, located at approximately 66.5 degrees north latitude, marks the southernmost/northernmost point where polar night (the sun that never rises) can be observed at the winter solstice depending on whether you are north or south of the Arctic Circle. The same goes for the midnight sun.