The winter solstice occurs around December 21 or 22 in the Northern Hemisphere, marking the shortest day and longest night of the year. This event happens when the Earth's axial tilt is farthest from the sun, resulting in minimal sunlight for that day. Many cultures celebrate the winter solstice with various traditions and festivals, recognizing the return of longer days. It is also significant in astronomy, as it signifies the start of winter and the gradual increase of daylight leading up to the spring equinox.