JACKSON, Wyo. — Happy winter solstice! Sunday, Dec. 21, marks the first day of winter and the shortest day of the year in the Northern Hemisphere.
Last year, Buckrail spoke with Wyoming Stargazing Executive Director Samuel Singer to unpack all things solstice, including general misconceptions about the astronomical event.
“The winter solstice is the 24-hour period where we have the largest percentage of dark hours after the sun sets and before the sun rises, and the shortest amount of daylight hours between the time of sunrise and sunset,” Singer said. “For astronomers, its awesome. We get more hours to observe the night time sky than any other night of the year.”
Singer explained that the earth’s northern hemisphere is pointing away from the sun at 23.5 degrees as it’s rotating around the sun, which causes the season of winter. Then, in the summer, the earth is angled 23.5 degrees toward the sun, which causes warmer, longer days.
According to Singer, it’s the earth’s tilt and its relationship with the arc of the sun’s solar radiation that changes the temperature of the earth. When the earth is pointed away from sun in the winter, the atmosphere doesn’t heat up as much because the sun’s angle of radiation is spread out over a longer distance. He shared an educational, rhyming phrase he learned to better understand the tricky topic of solstices: “Length of days and angles of rays, but nothing to do with how far away.”
Singer said that another misconception is that the winter solstice marks the first day of winter; he contends that it falls during the peak of winter.
“Our calendar uses these mid-point days, like the winter solstice, to define the beginning and ending of the seasons,” Singer said. “We should actually be using the cross-quarter days, the days that actually fall between the equinoxes and the solstices as the beginning and ending of the seasons.”
According to Singer, Halloween marks the beginning of winter, and the solstice marks the apex of winter. Then, starting next week, the days will gradually become longer and longer until Groundhog Day on Feb. 2, which is another cross-quarter day.
“Ancient peoples in Europe and Mesoamerica used the cross-quarter days to actually keep track of the changes of the seasons,” Singer said.
Singer explained that colder temperatures occurring later in the winter also causes the misconception that the winter solstice marks the beginning of winter. He said that a “seasonal lag” decreases temperatures during the second half of winter or after the solstice.
“It takes a couple of months for the earth to warm up and to cool off, as we approach and get into each season, which is why the coldest time of winter is not around the solstice,” Singer said. “It is usually a little bit later in the winter, like January or February, when we get down into the negatives. So, the atmosphere and the earth are still cooling off from the fall.”
This story runs annually.
