The winter solstice (boreal) –which this year (2020) will take place on Monday, December 21, at 11 hours and 2 minutes, Spanish peninsular time– marks the official start of the astronomical winter and a time of the year that, historically , has had a special significance. The word solstice, whose etymology leads us to the Latin term solstice, which means “still sun”, indicates a singular moment of the year in the passing of the sun through the celestial vault. On that day, the king star reaches its lowest height above the horizon, beginning from that moment on a lengthening of the time that runs from sunrise to sunset.
Although we refer to the winter solstice as the day shortest of the year (understood as day the time in which the solar disk is – even partially – above the horizon), if we look at the data of sunrise and sunset in an astronomical yearbook we will check how there are several days ahead and behind the solstice with the same duration. Astronomical factors, such as the inclination of the ecliptic plane and the shape of the Earth’s orbit, as well as the fact that in the calendars and yearbooks of common use the ephemeris are indicated in hours and minutes, but not with the precision of seconds, explain the fact commented.
The popular proverb and Saint Lucia
In popular tradition, Saint Lucia of Syracuse – a Christian martyr on horseback between the 3rd and 4th centuries – is related precisely to the time of year when the nights stop getting shorter and the nights start to get longer. days, but if we analyze the sayings that allude to the saint, the date that her name day is celebrated (December 13) and the day of the solstice, which coincides with December 21 in 2020, but which, depending on the years, may vary Between the 20th and 23rd, there are some things that don’t seem to add up. What yes that It is logical that it has been related to the holy protector of sight – whose name derives from “light” -, with the passage of darkness (long nights) to the growth of the days (the arrival of clarity).
Let’s pause for a moment on some sayings that allude to the patron saint of the blind, oculists or dressmakers, among other groups: “For Santa Lucia, the longest night and the shortest day”, “For Saint Lucia, the night decreases and the day grows”, “For Saint Lucia, it grows a handful every day”. A boat soon, it seems clear that they refer to the day of the winter solstice, but that leads us to an important discrepancy of dates, since as noted, the day of Saint Lucia is December 13, and the solstice falls between the 20th and the 23rd of the last month of the year. The difference seems too great to think about an error of appreciation on the part of those who put these sayings into circulation, in medieval times.
So when do the days start to grow?
If we interpret the “day” to which the sayings refer to the day that we defined before, its growth begins to be detected either when the sun begins to rise a little earlier, or when it sets a little later. Returning to the ephemeris of astronomical yearbooks, although the hours of sunrise and sunset are different in each place, paying attention to the passage of the star in the sky, While the delay in the time of sunset usually falls, between December 6 and 9, the early departure does not occur until the beginning of January, already after the Three Kings Day. Neither circumstance occurs around December 13. What could be the reason for this discrepancy?
The date lag is due to the Gregorian calendar reform that took place in 1582. The calendar that had been used until then was the Julian one, named in honor of Julius Caesar, who over the centuries became out of phase with the astronomical cycle, forcing Pope Gregory XIII to change it to a more exact one. To correct the accumulated lag, an unprecedented decision was taken, since Ten days were eliminated from the calendar in one stroke, and from Thursday, October 4 of that year, 1582, it was changed to Friday, October 15.
In the years prior to the Gregorian reform, Julian December 13 was equivalent to December 23 of our current calendar; that is to say, it coincided in dates with the approximate moment in which the winter solstice takes place. It is precisely at that time of year when, as one of the three aforementioned sayings points out, we have “the longest night and the shortest day.” In the days before and after the solstice the growth of the days it’s hard to appreciate. We begin to notice it –on clear days– at dusk, since the sunset is delayed very slowly. The process is accelerated from January 10, to which must also be added the progressive advance of the sunrise.
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