Q: 24 hours in a day is not exact, so to compensate for the difference we have leap years, correct? But if every day there are a few more seconds or minutes, would it not then slowly change our days and nights?
Answer: Leap years were developed in the Julian calendar, which preceded the calendar we currently use, called the Gregorian calendar. Since the average solar year is about 365¼ days, every fourth year an extra day is needed to be added to balance it out. However, if you’re going to be more precise, the average solar year is 11 minutes and 14 seconds shorter than that, so over time the numbers still got out of whack.
Between the time the Julian calendar was devised in 46 B.C. and the time the Gregorian calendar came about in 1582 A.D., the calendar had gotten out of phase, meaning that the vernal equinox was arriving earlier than it should. Pope Gregory XII decreed that those days would be dropped from the year, and from then on a revised calendar would be used. So the day after Oct. 4, 1582, became Oct. 15, 1582, in Spain, Portugal, most of Italy, and the Polish Lithuanian Commonwealth, according to an article at LiveScience.com, a website devoted to science.
“Other Catholic countries and colonies soon followed,” according to the article. “Other nations objected to losing 10 days, but often that was due more to not wanting to indicate fellowship with the Catholic Church than being concerned with scientific accuracy. Some nations wouldn’t switch over for hundreds of years. The British Empire (including the American colonies) did not adopt the change until 1752.” So if you stayed up late on the night of Wednesday, Sept. 2, 1752, the next day would have been Thursday, Sept. 14, according to the National Archives in the U.K. (by that time, the empire and colonies had gotten 11 days out of step with the rest of Europe).
To keep the problem from coming up again, in the Gregorian calendar, years that are divisible by four are leap years, but the century years are not leap years unless they are divisible by 400. So the year 2000, and the year 1600, both of which are divisible by 400, were leap years, but 1700, 1800 and 1900 were not leap years.
“While in a 2000-year period, the Julian calendar had 500 leap years; the Gregorian calendar only has 485,” according to LiveScience.com. “This change was based on a calculation that an average year length is 365.2425 days, which was pretty close: the modern measured value is 365.24219 days. This small difference, coupled with the precession of the equinoxes, amount to the Gregorian calendar shifting a day out of sync after 7,700 years. We have a while to wait until this discrepancy causes any problems.”
The next leap day is next month, on Feb. 29.
Q: When will you list shredding events?
Answer: Our next list of shredding events will run in the Feb. 1 SAM column. During shredding season, we run lists on the first Saturday of the month. Anyone holding such an event can let us know at firstname.lastname@example.org to be included.