IN OCTOBER 1582, many people in Europe
lost 10 days of their lives. After years of floating seasons
and religious occasions, Pope Gregory XIII decided to change
the Julian calendar. The Julian Calendar, named after its creator
Julius Caesar, was in use from 45bc. Caesar had improved things
by switching from the traditional lunar calendar to one guided
by the sun, but there were still problems with the calendar.
Gregory XIII reformed the calendar, primarily to ensure
that religious holidays fell at the proper time of year.
According to the Julian Calendar, the year was 365 and 1/4 days
in length. A solar year is actually 365 days, 5 hours, 48 minutes
and 46 seconds in length, 11 minutes and 14 seconds shorter
than the Julian calculation. There were also too many leap years
inserted into the Julian Calendar - one every four years. The
combination of too many leap years and 11 extra minutes each
year meant that Easter would eventually take place in the winter.
In 1582, Gregory XIII decided to eliminate 10 days from October
by making 15 October the day after 4 October. By removing these
days, the spring equinox was set at 21 March.
Under the Julian Calendar, a leap year occurred every four years.
Under the new, more precise calendar, a leap year occurred every
four years, except in centennial years not evenly divisible
by 400 (thus, 1600 and 2000 would be leap years, but 1700, 1800
and 1900 would not be).
The new calendar also created a fixed day for the New Year.
This anniversary had been celebrated on numerous dates. Julius
Caesar had used 1 January, but the Church had since changed
that date to 25 March. The Gregorian Calendar reverted back
to the date of 1 January.
The Gregorian Calendar is differ from the solar year by only
26 seconds, which only adds up to one day every 3,323 years.
The Gregorian Calendar went into effect in 1582 in all Roman
Catholic countries. Protestant and non-Christian countries were
slower to adopt the calendar - Great Britain and her possessions
adopted the calendar in 1752, Sweden in 1753, Japan in 1873
and China in 1912.
The Gregorian Calendar is still in effect today throughout the
world except in Muslim countries, where the calendar is based
on predicted lunar visibility.
This article originally appeared as part of a larger piece
on the 1580s in our October/November 2001