The winter solstice heralds the beginning of winter, and gives us the longest nighttime of the year. This fact alone is the reason there are so many winter holidays that center around lights. My husband was born on the winter solstice, which usually falls on December 21st, but this year it’s the 22nd. That will correct itself next year, which is a leap year. But the solstice really isn’t a “day.” Let’s learn more about the winter solstice.
1. IT HAPPENS ON DECEMBER 22 UTC THIS YEAR.
The date of the winter solstice varies from year to year, and can fall anywhere between December 20 and December 23, with the 21st or 22nd being the most common dates. The reason for this is because the tropical year—the time it takes for the sun to return to the same spot relative to Earth—is different from the calendar year. The next solstice occurring on December 20 will not happen until 2080, and the next December 23 solstice will not occur until 2303.
2. IT HAPPENS AT A SPECIFIC, BRIEF MOMENT.
Not only does the solstice occur on a specific day, but it also occurs at a specific time of day, corresponding to the instant the North Pole is aimed furthest away from the sun on the 23.5 degree tilt of the Earth’s axis. This is also the time when the sun shines directly over the Tropic of Capricorn. In 2015, this moment occurs at 4:48 UTC (Coordinated Universal Time). For those of us on Eastern Standard Time, the solstice will occur at 11:48 PM on December 21 (though officially it happens the day following). And regardless of where you live, the solstice happens at the same moment for everyone on the planet.