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.
Leap year In the Gregorian calendar, the standard calendar in most of the world, most years that are multiples of 4 are leap years. In each leap year, the month of February has 29 days instead of 28. Adding one extra day in the calendar every four years compensates for the fact that a period of 365 days is shorter than a tropical year by almost 6 hours.[4] Some exceptions to this basic rule are required since the duration of a tropical year is slightly less than 365.25 days. The Gregorian reform modified the Julian calendar's scheme of leap years as follows:
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]
July July is the seventh month of the year (between June and August) in the Julian and Gregorian Calendars and the fourth of seven months to have a length of 31 days. It was named by the Roman Senate in honour of Roman general Julius Caesar, it being the month of his birth. Prior to that, it was called Quintilis, being the fifth month of the 10-month calendar.