Last week I pointed out that Saint Lucy’s feast day (December 13) is celebrated differently in Sweden and in Sicily. Sicily has processions and food, but Sweden has candles and breakfast in bed. Generally (meaning if you look it up on Google), this Swedish idea is attributed to the “fact” that Saint Lucy’s feast day used to be the shortest day of the year, before the Gregorian calendar was brought into use. The calendar was changed in October of 1580; eleven days were dropped. The day after October 4 was October 15 and on that day Teresa of Avila was declared a saint.

Now a little math will show that December 13 plus eleven days would give December 24 not December 21. What’s going on? To make sense of this let’s discuss the calendar and the necessity for changing it.

Before the Gregorian calendar, the western world used the Julian calendar, so-called because it was arranged by, or at least during the reign of, Julius Caesar. At that time the calendar was so out of whack that the months of the year were upside down. June during the shortest days and December during the longest. Julius was responsible for restarting the year, adding some months and inserting a leap year every four years to make time behave.

By the time 400 years had passed his calendar had gotten out of sync with the heavens again. The problem was that an extra day every four years is too much. Life was still so chaotic though that when this was noticed by the Church, as she came out of the catacombs, the assumption was made that the Julian calendar worked correctly but someone had gotten the starting date off by several days. Hence at the Council of Nicaea in 325 A.D. the calendar was reset by those days but otherwise unchanged.

The problem constantly faced by the Church was setting the date of Easter correctly. She wanted it to be on the first Sunday after the first full moon after the vernal equinox. (There were factions but I’m ignoring them.) This formulation had been settled on at the same Council. However, over the next thousand years the calendar began to drift again. This time the Church knew it was not because of initial mistakes. The heavenly year was actually shorter than the calendar year over centuries. But no-one was quite certain how to fix the problem.

The reason that the Church knew so clearly, that the calendar was out of sync with the heavens, is that they had a device which showed the date of the equinox, a sort of churchly Stonehenge.* A hole in a wall in the Vatican allowed the sun to shine through. The change of the position of the sun over a year meant, that if its bright position was marked in some way at some moment on March 21, then that shining light would always hit that spot on every March 21. It was dismaying over a thousand years to watch the light shine on that spot on successively earlier days of the year.

Hence we can see that in the 1100’s and 1200’s, when Sweden was internalizing her conversion to Christianity, the discrepancy in the sky would be shorter than it was in the late 1500’s, perhaps eight or nine days, rather than eleven. That puts Saint Lucy’s feast right in the running for happening on the shortest day and allowed (maybe) the lovely custom to develop whereby a young girl wearing candles in her hair brings you breakfast in bed. Don’t I wish!

*If this change in the position of the sun is confusing you go to APOD and look at some of these pictures and read the explanation of analemmas.

https://apod.nasa.gov/apod/ap160822.html  this one includes a solar eclipse  That takes planning!

https://apod.nasa.gov/apod/ap150923.html  helpful for showing how the sun is going to be below the horizon – this pic is from Antarctica

https://apod.nasa.gov/apod/ap130922.html  in Greece over ruins