when did greece change to the gregorian calendar
Adoption of the Gregorian calendar Other countries of eastern Europe, most notably Eastern Orthodox countries, adopted the Gregorian calendar in the 1910s or early 1920s. The last country of Eastern Orthodox Europe to adopt the Gregorian calendar for civil purposes was Greece, at the time under military administration following the 11 September 1922 Revolution, with Wednesday 15 February 1923 being followed by Thursday 1 March 1923.[13] The Soviet decree expressly limited the reform to lay (i.e. non-religious) matters, as did the Greek decree. None of these reforms affected the dates of religious holidays. (See below.)
Hebrew calendar AM 5779 began at sunset on 9 September 2018 and will end at sunset on 29 September 2019.[2]
February 29 A leap day is observed because a complete revolution around the Sun takes approximately 6 hours longer than 365 days (8,760 hours). A leap day compensates for this lag, realigning the calendar with the Earth's position in the Solar System; otherwise, seasons would occur earlier than intended in the calendar year. The Julian calendar used in Christendom until the 16th century added a leap day every four years; but this rule adds too many days (roughly 3 every 400 years), making the equinoxes and solstices shift gradually to earlier dates. By the 16th century the vernal equinox had drifted to March 11, and the Gregorian calendar was introduced both to shift it back by omitting several days, and to reduce the number of leap years via the "century rule" to keep the equinoxes more or less fixed and the date of Easter consistently close to the vernal equinox.[1][2]
Gregorian calendar The Gregorian calendar is the most widely used civil calendar in the world.[1][2][Note 1] It is named after Pope Gregory XIII, who introduced it in October 1582. The calendar spaces leap years to make the average year 365.2425 days long, approximating the 365.2422 day tropical year that is determined by the Earth's rotation around the Sun. The rule for leap years is as follows: