What is "julian calendar"

Julian \Jul"ian\ (?; 277)

1. [L. Julianus, fr. Julius. Cf. July, Gillian.] Relating to, or derived from, Julius C[ae]sar.

   Julian calendar, the calendar as adjusted by Julius C[ae]sar, in which the year was made to consist of 365 days, each fourth year having 366 days.

   Julian epoch, the epoch of the commencement of the Julian calendar, or 46

3. Julian period, a chronological period of 7,980 years, combining the solar, lunar, and indiction cycles (28 x 19 x 15 = 7,980), being reckoned from the year 4713 B. C., when the first years of these several cycles would coincide, so that if any year of the period be divided by 28, 19, or 15, the remainder will be the year of the corresponding cycle. The Julian period was proposed by Scaliger, to remove or avoid ambiguities in chronological dates, and was so named because composed of Julian years.

   Julian year, the year of 365 days, 6 hours, adopted in the Julian calendar, and in use until superseded by the Gregorian year, as established in the reformed or Gregorian calendar.

Calendar \Cal"en*dar\, n. [OE. kalender, calender, fr. L. kalendarium an interest or account book (cf. F. calendrier, OF. calendier) fr. L. calendue, kalendae, calends. See Calends.]

1. An orderly arrangement of the division of time, adapted to the purposes of civil life, as years, months, weeks, and days; also, a register of the year with its divisions; an almanac.

2. (Eccl.) A tabular statement of the dates of feasts, offices, saints' days, etc., esp. of those which are liable to change yearly according to the varying date of Easter.

3. An orderly list or enumeration of persons, things, or events; a schedule; as, a calendar of state papers; a calendar of bills presented in a legislative assembly; a calendar of causes arranged for trial in court; a calendar of a college or an academy.

   Note: Shepherds of people had need know the calendars of tempests of state.
   --Bacon.

   Calendar clock, one that shows the days of the week and month.

   Calendar month. See under Month.

   French Republican calendar. See under Vend['e]miaire.

   Gregorian calendar, Julian calendar, Perpetual calendar. See under Gregorian, Julian, and Perpetual.

The Julian calendar, introduced by Julius Caesar in 46 BC (708 AUC), was a reform of the Roman calendar. It took effect in 45 BC (AUC 709), shortly after the Roman conquest of Egypt. It was the predominant calendar in the Roman world, most of Europe, and in European settlements in the Americas and elsewhere, until it was refined and gradually replaced by the Gregorian calendar, promulgated in 1582 by Pope Gregory XIII. The Julian calendar gains against the mean tropical year at the rate of one day in 128 years. For the Gregorian the figure is one day in 3,226 years. The difference in the average length of the year between Julian (365.25 days) and Gregorian (365.2425 days) is 0.002%.

The Julian calendar has a regular year of 365 days divided into 12 months, as listed in Table of months. 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 a few minutes shorter than 365.25 days, the calendar did not compensate for this difference. As a result, the year gained 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. Consequently, the Julian calendar is currently (since 14 March 1900 Gregorian/1 March Julian and until 28 February 2100 Gregorian/15 February Julian) 13 days behind the Gregorian calendar.

The Julian calendar has been replaced as the civil calendar by the Gregorian calendar in almost all countries which formerly used it, although it continued to be the civil calendar of some countries into the 20th century. Egypt converted on 20 December 1874/1 January 1875. Turkey switched (for fiscal purposes) on 16 February/1 March 1917. Russia changed on 1/14 February 1918. The original proposal had been to drop 24 hours every year, spreading the change over thirteen years, and to drop the leap day in years exactly divisible by 128 (e.g. 1920). Greece made the change for civil purposes on 16 February/1 March 1923 - the national day (25 March), which was a religious holiday, was to remain on the old calendar. However, this created confusion and on 10/23 March 1924 the church began using this "new" or "political" calendar for fixed religious feasts. Seven leap days are omitted in 900 years. This caused Easter, for which the calculation was unaffected, to fall in April or May. Most Christian denominations in the west and areas evangelised by western churches have also replaced the Julian calendar with the Gregorian as the basis for their liturgical calendars. However, most branches of the Eastern Orthodox Church still use the Julian calendar for calculating the dates of moveable feasts, including Easter (Pascha). Some Orthodox churches have adopted the Revised Julian calendar for the observance of fixed feasts, while other Orthodox churches retain the Julian calendar for all purposes. The Julian calendar is still used by the Berber people of North Africa, and on Mount Athos. In the form of the Alexandrian calendar, it is the basis for the Ethiopian calendar, which is the civil calendar of Ethiopia.

During the changeover between calendars and for some time afterwards, dual dating was used in documents and gave both old style and new style dates.