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| Pope Gregory XIII |
(by the Julian Calendar)
By Moristotle
Tomorrow will be the 439th birthday of the Gregorian Calendar, which was adopted in October 1582, in order to correct a problem with the Julian Calendar’s calculation of the average year as having 365.25 days.The Wikipedia entry on the Julian Calendar explains the problem:
[365.25 days] is more than the actual solar year value of 365.24219 days…which means the Julian calendar gains a day every 128 years. For any given event during the years from 1901 to 2099 inclusive, its date according to the Julian calendar is 13 days behind its corresponding Gregorian date.The Pope’s adjustment resulted in the more accurate average of 365.2425 days per year. His solution, besides jumping overnight from Thursday, October 4, to Friday, October 15, was to reduce the number of leap years, excluding the years ending in 00 that are not divisible integrally by 400. And to think some people have trouble just adjusting their clocks for daylight savings!
The problem with the Julian Calendar (for Roman Catholics) was mainly liturgical, apparently.
[T]he excess leap days introduced by the Julian algorithm had caused the calendar to drift such that the (Northern) spring equinox was occurring well before its nominal 21 March date. This date was important to the Christian churches because it is fundamental to the calculation of the date of Easter. To reinstate the association, the reform advanced the date by 10 days: Thursday 4 October 1582 was followed by Friday 15 October 1582.Wikipedia lists what year it is in over 30 other calendars, including the geologic Holocene Calendar (12021) and the computer Unix Index (1609459200 – 1640995199). Please don’t tell Goines.
| Copyright © 2021 by Moristotle |
Finally, something I can get my brain around. I was aware of the discrepancy in the calendars, and of course the problem with "holy days" for the religionists. The Romans had the same problem, and dealt with it by the much-misunderstood and misused "moveable feast". Not moveable as in place but in time. They had specialists who calculated what calendar day a particular feast should be held on based on the actual astronomical date. Our Easter is such a feast; it's date is the first Sunday after the full moon on or following the (Northern) Spring Equinox.
ReplyDeleteThank you, Roger, for elaborating on calendar adjustments and the demands of religious festivities, around which demands Goines has given up the attempt to wrap his own brain.
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