|The Julian year was 11 min and 14 sec longer
than the solar year. This discrepancy accumulated until by 1582 the vernal
equinox (see Ecliptic) occurred 10 days early and church holidays did not
occur in the appropriate seasons. To make the vernal equinox occur on or
about March 21, as it had in AD 325, the year of the First Council of
Nicaea, Pope Gregory XIII issued a decree dropping 10 days from the
calendar. To prevent further displacement he instituted a calendar, known
as the Gregorian calendar, that provided that century years divisible
evenly by 400 should be leap years and that all other century years should
be common years. Thus, 1600 was a leap year, but 1700 and 1800 were common
The Gregorian calendar, or New Style calendar, was slowly adopted throughout Europe. It is used today throughout most of the Western world and in parts of Asia. When the Gregorian calendar was adopted in Great Britain in 1752, a correction of 11 days was necessary; the day after September 2, 1752, became September 14. Britain also adopted January 1 as the day when a new year begins. The Soviet Union adopted the Gregorian calendar in 1918, and Greece adopted it in 1923 for civil purposes, but many countries affiliated with the Greek church retain the Julian, or Old Style, calendar for the celebration of church feasts.
The Gregorian calendar is also called the Christian calendar because it uses the birth of Jesus Christ as a starting date. Dates of the Christian era (see Chronology) are often designated AD (Latin anno domini, "in the year of our Lord") and BC (before Christ). Although the birth of Christ was originally given as December 25, 1 BC, modern scholars now place it about 4 BC.
Because the Gregorian calendar still entails months of unequal length, so that dates and days of the week vary through time, numerous proposals have been made for a more practical, reformed calendar. Such proposals include a fixed calendar of 13 equal months and a universal calendar of four identical quarterly periods. Thus far, none has been adopted
"Calendar," Microsoft(R) Encarta(R) 98 Encyclopedia. (c) 1993-1997 Microsoft Corporation. All rights reserved.