1582 Establishments: Gregorian Calendar

 
9781477426647: 1582 Establishments: Gregorian Calendar
View all copies of this ISBN edition:
 
 

What's so special about Gregorian Calendar? In this new, compelling book from author Marlene Coffey, find out more about Gregorian Calendar ... The Gregorian calendar, also called the Western calendar and the Christian calendar, is the internationally accepted civil calendar. It was introduced by Pope Gregory XIII, after whom the calendar was named, by a decree signed on 24 February 1582; the decree, a papal bull, is known by its opening words, Inter gravissimas. The reformed calendar was adopted later that year by a handful of countries, with other countries adopting it over the following centuries. The motivation for the Gregorian reform was that the Julian calendar assumes that the time between vernal equinoxes is 365.25 days, when in fact it is presently almost exactly 11 minutes shorter. The error between these values accumulated at the rate of about three days every four centuries, resulting in the equinox being on March 11 and moving steadily earlier in the Julian calendar at the time of the Gregorian reform. Because the spring equinox was tied to the celebration of Easter, the Roman Catholic Church considered this steady movement in the date of the equinox undesirable. The Gregorian calendar reform contained two parts: a reform of the Julian calendar as used prior to Pope Gregory's time and a reform of the lunar cycle used by the Church, with the Julian calendar, to calculate the date of Easter. The reform was a modification of a proposal made by the Calabrian doctor Aloysius Lilius. Lilius' proposal included reducing the number of leap years in four centuries from 100 to 97, by making 3 out of 4 centurial years common instead of leap years: this part of the proposal had been suggested before by, among others, Pietro Pitati. Lilio also produced an original and practical scheme for adjusting the epacts of the moon when calculating the annual date of Easter, solving a long-standing obstacle to calendar reform. The Gregorian calendar modified the Julian calendar's regular cycle of leap years, years exactly divisible by four, including all centurial years, as follows: Every year that is exactly divisible by four is a leap year, except for years that are exactly divisible by 100; the centurial years that are exactly divisible by 400 are still leap years. For example, the year 1900 is not a leap year; the year 2000 is a leap year. In addition to the change in the mean length of the calendar year from 365.25 days to 365.2425 days, a reduction of 10 minutes 48 seconds per year, the Gregorian calendar reform also dealt with the accumulated difference between these lengths. Between AD 325, and the time of Pope Gregory's bull in 1582, the vernal equinox had moved backward in the calendar, until it was occurring on about 11 March, 10 days earlier. The Gregorian calendar therefore began by skipping 10 calendar days, to restore March 21 as the date of the vernal equinox. So, what seperates this book from the rest? A comprehensive narrative of Gregorian Calendar, this book gives a full understanding of the subject. A brief guide of subject areas covered in "1582 Establishments - Gregorian Calendar" include - - Gregorian calendar - Computus - Coptic calendar - Ethiopian calendar - Dual dating - Old Style and New Style dates - 7 Day Week - Anno Domini Find out more of this subject, it's intricacies and it's nuances. Discover more about it's importance. Develop a level of understanding required to comprehend this fascinating concept. Author Marlene Coffey has worked hard researching and compiling this fundamental work, and is proud to bring you "1582 Establishments - Gregorian Calendar" ... Read this book today ...

"synopsis" may belong to another edition of this title.

(No Available Copies)

Search Books:



Create a Want

If you know the book but cannot find it on AbeBooks, we can automatically search for it on your behalf as new inventory is added. If it is added to AbeBooks by one of our member booksellers, we will notify you!

Create a Want