A group of people gathered in Denver, Colorado to celebrate the Winter Solstice on Friday. /VCG Photo

They held a drumming ceremony to symbolically drum up the sun and say goodbye to the darkness. /VCG Photo

The Winter Solstice marks the day with the shortest period of daylight and the longest night of the year. It happens when one of the Earth's poles has its maximum tilt away from the Sun. /VCG Photo

This year's Winter Solstice for Denver was at 3:22 p.m. on December 21. The length of sunlight time was five hours and 38 minutes shorter than on the summer solstice in June. /VCG Photo

The Winter Solstice is also celebrated in many other parts of the world as the start of the gradual return of longer daylight hours and shorter nights. In China, the Winter Solstice, also known as the Dongzhi Festival is celebrated when families get together and eat festive food such as sweet rice dumplings. /VCG Photo