how many days in a julian calendar year
Julian calendar The Julian calendar has a regular year of 365 days divided into 12 months, as listed in the table below. A leap day is added to February every four years. The Julian year is, therefore, on average 365.25 days long. It was intended to approximate the tropical (solar) year. Although Greek astronomers had known, at least since Hipparchus, a century before the Julian reform, that the tropical year was slightly shorter than 365.25 days, the calendar did not compensate for this difference. As a result, the calendar year gains about three days every four centuries compared to observed equinox times and the seasons. This discrepancy was corrected by the Gregorian reform of 1582. The Gregorian calendar has the same months and month lengths as the Julian calendar, but, in the Gregorian calendar, years evenly divisible by 100 are not leap years, except that years evenly divisible by 400 remain leap years.[3] Consequently—since 16 February Julian/1 March 1900 Gregorian and until 15 February Julian/28 February 2100 Gregorian—the Julian calendar is currently 13 days behind the Gregorian calendar.
The Pale The word pale derives ultimately from the Latin word
Week The seven-day week seems to have been adopted, at different stages, by the Persian Empire, in Hellenistic astrology, and (via Greek transmission) in Gupta India and Tang China.[b][citation needed]
Standard deviation Let X be a random variable with mean value Î¼:
Exponentiation Any nonzero number raised to the 0 power is 1:[11]
History of calendars The Gregorian calendar was introduced as a refinement of the Julian calendar in 1582, and is today in worldwide use as the de facto calendar for secular purposes.