You might have already seen snow and cozied up with cups of cocoa, but winter doesn't officially start until 5:44 a.m. EST this Wednesday, December 21. This is when the winter solstice occurs, marking the shortest day (or the day with the least amount of sunlight) and longest night of the year.According to EarthSky , solstices occur because of the Earth's movement around the sun and how it tilts on its axis. On Wednesday, the Northern Hemisphere will be tilted as far away from the sun as possible. As we move closer to spring and the Earth tilts closer to the sun, the days will seem longer.Some theories suggest that Stonehenge was designed in alignment with the solstices, but The Old Farmer's Almanac says that these are still unsubstantiated.One thing that is for sure: You should celebrate with candy cane bagels, peppermint mochas, and viewings of Home Alone, The Holiday, and Love Actually. And if you're lucky enough to have a working fireplace, toss some logs on. After all, spring won't officially start until March 20, 2017, when the spring equinox occurs. So, for better or worse, we've got a solid three months of winter to endure.