Different calendars and christmas

The Roman calendar that had been in use since the eighth century B.C. originally started the year on March 1 and had 10 months as the names of the months themselves indicate, September (7), October (8), November (9) and December (10). Eventually two months were added, Januarius and Februarius, and the year was started on January. However, it was only 355 days long so it had over ten days error and the seasons and the calendar over the years continued to lose their correct relationship.

JULIAN CALENDAR

JULIUS CAESAR FINALLY in 46 B.C. had the Greek astronomer Sosigenes establish the length of the solar calendar at 365 and one quarter days (365.25). Every fourth year was to add one day to keep the quarter days accurate and this has now become our leap year with February 29. The Julian Calendar was introduced on January 1, 45 B.C. and the next year Caesar was honored by having the seventh month renamed in his honor as July. A later Roman Emperor, Augustus Caesar, corrected the leap year system in A.D. 8 and in his honor a month was renamed August. The Julian calendar consisted of cycles of three 365-day years followed by a 366-day leap year. Around 9 BC, it was found that the priests in charge of computing the calendar had been adding leap years every three years instead of the four decreed by Caesar (Vardi 1991, p. 239). As a result of this error, no more leap years were added until 8 AD. Leap years were therefore 45 BC, 42 BC, 39 BC, 36 BC, 33 BC, 30 BC, 27 BC, 24 BC, 21 BC, 18 BC, 15 BC, 12 BC, 9 BC, 8 AD, 12 AD, and every fourth year thereafter.

But the Julian year of 365 days and 6 hours exceeds the true solar year of 365.2422 days or 365 days 5 hours 49 minutes and 46 seconds by the amount of 11 minutes 14 seconds. The difference is about 0.0078 of a day per year or about one day in 128 years. Over a period of 1,500 years the calendar was again getting out of step with the natural seasons by about ten days.

Christmas, which had been celebrated on many different dates was finally fixed on December 25th by Bishop Liberius of Rome.

In 354 A.D. he chose the date to replace a Roman pagan festival of sun-god worship with Christ's Mass, a Christian event.

GREGORIAN CALENDAR

FINALLY POPE GREGORY XIII in 1582 introduced changes to correct the error in the Julian Calendar. To restore the vernal or spring equinox to March 21st he eliminated the 10 days from March 11 to 21 in 1582 so the dates March 12 to 20 never existed in 1582, at least not in Roman Catholic countries. Some Protestant countries like England and Sweden adopted the new calendar only in 1752 so there was 11 days difference by then. Russia, however, did not follow suit until 1918, when January 31, 1918 was immediately followed by February 14th. In fact, however, the USSR is not on the Gregorian calendar, but on a more accurate one of their own devising. The USSR calendar is designed to more closely approximate the true length of the tropical year, thus has one additional rule for when a year is a leap year. It will remain in synchronization with the Gregorian calendar for thousands more years, by which time one or both will have probably fallen into disuse. Similarly, Iranian calendar is also a more accurate version of the Gregorian calendar.

The calendar currently in worldwide use for secular purposes based on a cycle of 400 years comprising 146,097 days, giving a year of average length 365.2425 days. The Gregorian calendar is a modification of the Julian calendar in which leap years are omitted in years divisible by 100 but not divisible by 400. By this rule, the year 1900 was not a leap year (1900 is divisible by 100 and not divisible by 400), but the year 2000 will be a leap year (2000 is divisible by 400).

The Orthodox and Eastern rite churches such as the Ukrainian have maintained the Julian Calendar for ecclesiastical purposes into this century.

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