Calendar 2008 - Gregorian calendar; photo wallpapers: The
Gregorian calendar is the most widely used calendar in the world. A
modification of the Julian calendar, it was first proposed by the
Calabrian doctor Aloysius Lilius, and was decreed by Pope Gregory XIII,
for whom it was named, on 24 February 1582 via the papal bull Inter
gravissimas. Years in the calendar are numbered from the traditional
birth year of Jesus, which has been labeled the "anno Domini" (AD) era,
and is sometimes labeled the "common era" or the "Christian Era" (CE).
The Gregorian Calendar was devised both because the mean Julian
Calendar year was slightly too long, causing the vernal equinox to
slowly drift backwards in the calendar year, and because the lunar
calendar used to compute the date of Easter had grown conspicuously in
error as well. The Gregorian calendar system dealt with these problems
by dropping a certain number of days to bring the calendar back into
synchronization with the seasons, and then slightly shortening the
average number of days in a calendar year, by omitting three Julian
leap-days every 400 years. The days omitted are in the century years
(specifically: 29 February 1700, 1800, 1900; 2100, 2200, 2300; 2500,
2600, 2700; 2900, etc.).