Gregorian calendar

  • 2020 in various gregorian calendar
    2020
    mmxx
    ab urbe condita2773
    armenian calendar1469
    ԹՎ ՌՆԿԹ
    assyrian calendar6770
    bahá'í calendar176–177
    balinese saka calendar1941–1942
    bengali calendar1427
    berber calendar2970
    british regnal year68 eliz. 2 – 69 eliz. 2
    buddhist calendar2564
    burmese calendar1382
    byzantine calendar7528–7529
    chinese calendar己亥(earth pig)
    4716 or 4656
        — to —
    庚子年 (metal rat)
    4717 or 4657
    coptic calendar1736–1737
    discordian calendar3186
    ethiopian calendar2012–2013
    hebrew calendar5780–5781
    hindu calendars
     - vikram samvat2076–2077
     - shaka samvat1941–1942
     - kali yuga5120–5121
    holocene calendar12020
    igbo calendar1020–1021
    iranian calendar1398–1399
    islamic calendar1441–1442
    japanese calendarreiwa 2
    (令和2年)
    javanese calendar1953–1954
    juche calendar109
    julian calendargregorian minus 13 days
    korean calendar4353
    minguo calendarroc 109
    民國109年
    nanakshahi calendar552
    thai solar calendar2563
    tibetan calendar阴土猪年
    (female earth-pig)
    2146 or 1765 or 993
        — to —
    阳金鼠年
    (male iron-rat)
    2147 or 1766 or 994
    unix time1577836800 – 1609459199

    the gregorian calendar is the calendar used in most of the world.[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 revolution around the sun. the rule for leap years is:

    every year that is exactly divisible by four is a leap year, except for years that are exactly divisible by 100, but these centurial years are leap years if they are exactly divisible by 400. for example, the years 1700, 1800, and 1900 are not leap years, but the years 1600 and 2000 are.[2]

    the calendar was developed as a correction to the julian calendar,[note 1] shortening the average year by 0.0075 days to stop the drift of the calendar with respect to the equinoxes.[3] to deal with the 10 days' difference (between calendar and reality) that this drift had already reached, the date was advanced so that 4 october 1582 was followed by 15 october 1582. there was no discontinuity in the cycle of weekdays or of the anno domini calendar era.[note 2] the reform also altered the lunar cycle used by the church to calculate the date for easter (computus), restoring it to the time of the year as originally celebrated by the early church.

    the reform was adopted initially by the catholic countries of europe and their overseas possessions. over the next three centuries, the protestant and eastern orthodox countries also moved to what they called the improved calendar, with greece being the last european country to adopt the calendar in 1923.[5] to unambiguously specify a date during the transition period, (or in history texts), dual dating is sometimes used to specify both old style and new style dates (abbreviated as o.s and n.s. respectively). due to globalization in the 20th century, the calendar has also been adopted by most non-western countries for civil purposes. the calendar era carries the alternative secular name of "common era".

  • description
  • gregorian reform
  • difference between gregorian and julian calendar dates
  • beginning of the year
  • dual dating
  • proleptic gregorian calendar
  • months
  • weeks
  • accuracy
  • proposed reforms
  • see also
  • notes
  • citations
  • references
  • external links

2020 in various Gregorian calendar
2020
MMXX
Ab urbe condita2773
Armenian calendar1469
ԹՎ ՌՆԿԹ
Assyrian calendar6770
Bahá'í calendar176–177
Balinese saka calendar1941–1942
Bengali calendar1427
Berber calendar2970
British Regnal year68 Eliz. 2 – 69 Eliz. 2
Buddhist calendar2564
Burmese calendar1382
Byzantine calendar7528–7529
Chinese calendar己亥(Earth Pig)
4716 or 4656
    — to —
庚子年 (Metal Rat)
4717 or 4657
Coptic calendar1736–1737
Discordian calendar3186
Ethiopian calendar2012–2013
Hebrew calendar5780–5781
Hindu calendars
 - Vikram Samvat2076–2077
 - Shaka Samvat1941–1942
 - Kali Yuga5120–5121
Holocene calendar12020
Igbo calendar1020–1021
Iranian calendar1398–1399
Islamic calendar1441–1442
Japanese calendarReiwa 2
(令和2年)
Javanese calendar1953–1954
Juche calendar109
Julian calendarGregorian minus 13 days
Korean calendar4353
Minguo calendarROC 109
民國109年
Nanakshahi calendar552
Thai solar calendar2563
Tibetan calendar阴土猪年
(female Earth-Pig)
2146 or 1765 or 993
    — to —
阳金鼠年
(male Iron-Rat)
2147 or 1766 or 994
Unix time1577836800 – 1609459199

The Gregorian calendar is the calendar used in most of the world.[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 revolution around the Sun. The rule for leap years is:

Every year that is exactly divisible by four is a leap year, except for years that are exactly divisible by 100, but these centurial years are leap years if they are exactly divisible by 400. For example, the years 1700, 1800, and 1900 are not leap years, but the years 1600 and 2000 are.[2]

The calendar was developed as a correction to the Julian calendar,[Note 1] shortening the average year by 0.0075 days to stop the drift of the calendar with respect to the equinoxes.[3] To deal with the 10 days' difference (between calendar and reality) that this drift had already reached, the date was advanced so that 4 October 1582 was followed by 15 October 1582. There was no discontinuity in the cycle of weekdays or of the Anno Domini calendar era.[Note 2] The reform also altered the lunar cycle used by the Church to calculate the date for Easter (computus), restoring it to the time of the year as originally celebrated by the early Church.

The reform was adopted initially by the Catholic countries of Europe and their overseas possessions. Over the next three centuries, the Protestant and Eastern Orthodox countries also moved to what they called the Improved calendar, with Greece being the last European country to adopt the calendar in 1923.[5] To unambiguously specify a date during the transition period, (or in history texts), dual dating is sometimes used to specify both Old Style and New Style dates (abbreviated as O.S and N.S. respectively). Due to globalization in the 20th century, the calendar has also been adopted by most non-Western countries for civil purposes. The calendar era carries the alternative secular name of "Common Era".