Why will December 21 be the longest night of 2023?
As winter approaches, the days get shorter and the nights get longer, with December 21st being the longest night of 2023. What is the phenomenon behind it?
The United States is enjoying the last days of autumn to make way for the coldest season of the year: Winter. Throughout the 12 months of the year, two equinoxes and two solstices occur around the globe, which mark the beginning of the seasons. The equinoxes correspond to spring and autumn, while the solstices correspond to winter and summer.
In the United States, which is located in the northern hemisphere, the spring and autumn equinoxes occur in March and September, respectively; while the summer and winter solstices take place in June and December. That said, the United States is preparing to welcome the winter solstice, which will start officially on December 21, sharp at 10:21 p.m. ET, according to official information from the National Weather Service (NWS)
As winter approaches, the days become shorter while the nights become longer, with December 21st being the longest night of the entire year, but why does this happen? Below, we explain.
Why will December 21 be the longest night of 2023?
The longest night of the year is a result of the tilt of the Earth and its position with respect to the Sun. During the winter solstice, the north pole leans away from the star, so there are fewer daylight hours and, therefore, the night becomes longer. Above the Polar Circle in the northern hemisphere night never ends for days or months depending on the location. According to Universe2go, most Americans will be able to enjoy only eight hours of daylight this December 21.
Once the winter solstice comes to an end and the spring equinox begins, the opposite effect will occur; that is, there will be more daylight hours because the northern hemisphere will now be more inclined towards the Sun. It is worth mentioning that in the countries of the southern hemisphere the effect is opposite. December 21 will represent the longest day of the year due to the arrival of summer, since the beginning of the seasons occur in opposite manner.
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In addition to offering fewer hours of light, the winter solstice has other effects that are quite easy to appreciate, such as the lengthening of shadows, as the Sun is lower in the sky, if it comes over the horizon.