Nonfiction is the New Black
The calendar worked perfectly—almost. The Julian year on average had 365 days and 6 hours. Every four years those six hours would be combined to make an extra day. But the solar year is actually 365 days, 5 hours, 48 minutes, and 46 seconds long. That difference of just over 11 minutes began to add up. By the 16th century, the discrepancy was more than 10 days.
Easter—which many Christians consider their most important festival—is based on the vernal equinox, the time in the spring when the sun crosses the equator, and when night and day are the same length. Pope Gregory XIII, who became pope in 1572, was concerned because the holiday was slowly drifting away from the vernal equinox. A decade later he had a solution. He began by advancing the calendar by 10 days. So someone going to sleep on the night of September 2 that year woke up on the morning of September 13! He also said that leap years would still occur every four years—with one exception. If a year is evenly divisible by 100 but not 400, it isn’t a leap year. So 1800 and 1900 weren’t leap years. 2000 was. 2100 and 2200 won’t be. In other words, leap years are omitted three times every 400 years. The result is that the vernal equinox is usually on March 21.
Some countries quickly adopted the new Gregorian calendar. Others didn’t. Greece only adopted it in 1923. That meant that for centuries you could stand on the border of one country and it would be, say, October 4. Take a couple of steps into another country and it would be October 14. Eventually, though, the Gregorian version became the world’s most commonly accepted calendar.
It isn’t quite perfect. There’s still a very very very very slight difference with the solar year. This difference will have to be addressed—in about 3,000 years.
Jim Whiting's most recent output is a six-book series about top European club soccer teams. Young fans may especially like FC Barcelona with superstar Lionel Messi on the cover.
For more information on this series and other books by Jim Whiting, pay a visit to his website.
Tomorrow Vicki Cobb will tell you about a young Polish girl who traveled to the Sorbonne to major in math and physics -- and became first in her class.