Dear Proper Green,
I heard that the shortest day of the year already happened, yet the winter solstice is this week. What is the winter solstice if not the shortest day of the year?
-Brett J., Fort Worth, TX
The shortest seeming day occurred during the first week of December (the exact day depending on where you live), when the earliest sunset of the year happened. But the shortest day in terms of total daylight is still December 21, this year’s winter solstice.
The winter solstice happens because the earth’s axis (the imaginary line running between the north and south poles) doesn’t stand perfectly straight in respect to the sun. The axis is tilted 23.5 degrees in one direction, which causes the seasons to change as the earth orbits the sun. For a few months during its orbit, the earth’s tilt points away from the sun, giving the northern hemisphere its winter. The winter solstice marks when the earth is both tilted away from the sun and furthest away from the sun in its orbit.
After the solstice, the daylight hours will gradually increase, but for now we’re dealing with the dark before it’s even dinner time. Less daylight can mean higher energy usage since we turn the lights on earlier and for longer, so be extra careful about needless usage. Besides turning off the lights, look for other ways to increase energy efficiency during winter time.