Friday, February 29, 2008

Leap Day   [David Freddoso]

From the Writers' Almanac (if you click through for the full version, you have to scroll down through the days of the week):

[T]he Earth does not orbit the sun in a nice round 365 days, but rather in 365 days, 5 hours, 48 minutes, and 45 seconds...[I]n the 13 century, a sick old friar named Roger Bacon sent a letter to the Pope. He had calculated the actual length of the solar year as slightly less than 365.25 days, and he pointed out that the Julian calendar was adding one leap day too many for every 125 years. The result was that Christians were celebrating holy days on the wrong dates...It wasn't until 1582 that Pope Gregory XIII hired a group of Jesuits to fix the calendar, and they came up with the complicated system of omitting the leap day at the beginning of each century, except for those centuries divisible by 400. When Pope Gregory made the change, the calendar was about 10 days off, so Gregory deleted 10 days from the year. People went to sleep on Thursday, Oct. 4 and woke up on Friday, Oct. 15.

...Protestant countries didn't adopt the new calendar until much later, and this meant that for a long time, if you crossed the border of certain European countries, you had to set your clock back or forward by at least 10 days. When Great Britain finally accepted the Gregorian calendar in 1751, 11 days had to be deleted from the year. The change led to antipapal riots, because people believed the pope had shortened their lives. Mobs gathered in the streets, chanting, "Give us back our 11 days!" When the British colonies in America made the change the following year, Ben Franklin wrote in an editorial, "Be not astonished, nor look with scorn, dear reader, at ... the loss of so much time. ... What an indulgence is here, for those who love their pillow, to lie down in peace on the second [day] of this month and not awake till the morning of the fourteenth."

The Gregorian calendar...is so accurate that we will have to wait until the year 4909 before our dates become out of step with the Earth's orbit by a full day.

02/29 03:17 PMShare