Calendar Converter

Calendar, a tool for measuring and recording of time

Calendar is the way used by the human people to measure the passing of time. The passing of time was always considered as constant. It would be irrational to think that some periods of time run slower of faster than others or that in some regions of our planet the time flows in a different way from that in other regions. Though, this obvious feeling which led Newton to characterize time as a constant never changing frame, does not hold. Einstein presented in 1905, in his Theory of Special Relativity, the dependence of time intervals to the velocity of the observer; this is the time dilation. Anyway, in the scale of the earthy velocities, the time dilation is indistinctive and consequently we consider the flow of time constant as our predecessors.

From the Old-Style (O.S) Julian to the New-Style (N.S) Gregorian Calendar

Julius Caesar introduced the Julian Calendar in 45 B.C. In this calendar every 4th year, which is called leao year, a whole day is added. Even so, the duration of the Julian Calendar was not exactly equal to the real duration of the tropical year, which is 365 days, 5 hours, 48 minutes and 45 seconds, resulting to a delay of one day every nearly 128 years. This led to the need of a new reformation from the Old Style (Julian) Calendar to the New Style (Gregorian) Calendar in 1582 in the Catholic countries.
The duration of the Julian Calendar (365 days and 6 hours or 365.25 days) is not exactly equal to the real duration of the tropical year, which is 365 days, 5 hours, 48 minutes and 45 seconds (or 365.24219879 days), resulting to a delay of nearly one day every 128 years. This led to the need of a new reformation from the Old Style - Julian Calendar to the New Style - Gregorian Calendar in 1582 in the Catholic countries. The weakness of the old calendar was evident as a shift with respect to the seasons. Pope Gregory XIII in 1582 under the scientific help of doctor Aloysius Lilius (Luigi Lilio) (1510-1576) undertook officially the great project of the calendar reform. The Pope with a bull ordered that the day following October 4, 1582 AD to be 15th of October, with 10 days lost. The Protestant countries admitted the calendar correction after nearly 2 centuries. United Kingdom and its colonies aligned with the Gregorian Calendar in September 2 of 1752 AD, deciding that the next day would be the 14th, with 11 days lost.
There are various web sites for converting Old-Style (Julian Calendar) dates to New-Style (Gregorian Calendar) dates, as the following:
• Convert between Old & New Style dates in UK
• Converting between Julian and Gregorian Calendar in One Step with a useful table indicating the switch date from the Julian Calendar to the Gregorian Calendar
• From Old-Style (Julian) to New-Style (Gregorian) taking also into account the specific country and the case of Old Calendarists
Obviously, both Julian and Gregorian Calendar are solar calendars, as they do not take into account the phases of the Moon and the synodic months. There are many other calendars, either desolated or in use, in the solar, lunar or lunisolar categories. This exemplifies the need for converting the widely used Gregorian dates (or Julian as far as past dates are concerned) to any of these other calendars

Old-Style Religious Calendars

In some countries, the religious authorities have decided to retain the Old-Style (Julian) Calendar for their feasts and celebrations, although the civil authorities have already adopted the New-Style (Gregorian) Calendar as their official Calendar. These are the cases of the Eastern Orthodox Churches, as Russian Church, which has placed the religious feasts 13 days later in the official civil Calendar, due to the 13 days divergence between the 2 Calendars. Obviously, this divergence will increase in the future. There is also a compromise policy in the case of the Orthodox Patriarchate of Constantinople and the Orthodox Greek Church, which have accepted the placement of all the feasts (Christmas etc.) in the N.S. Calendar, except for the feasts of the cycle of the Easter, whose dates are computed and placed according to the O.S. Calendar.

Converting from the Julian/ Gregorian to other Calendars

Next you can find some effective and valid date converter sites for converting any date from the Julian or Gregorian Calendar to a lot of predefined Calendars.
• Convert a date. This converter site has many available fields, each concerning a certain calendar. You can find among the fields, the Julian Date the Gregorian Date, the Weekday, the Hebrew Date, the Islamic Date, the Persian Date, the Kurdish Date, the Afghan Date, the Mayan Date (in Long Count, Haab and Tzolkin), the Baha’i Date, the Indian Civil Date, the French Republican Date and some technical dates, such as ISO Week and Day, Unix time value and Excel Serial Day. It starts with the current date in the various calendars and gives the opportunity to change any of the fields and see the corresponding values in all the remaining fields.
• Date Converter of the Academy of Episteme. This is a general environment about calendars, where you can find the current date or convert any date to various calendars: Gregorian, Old-Julian, Ancient Attic, Roman date, Byzantine-Annus Mundi & Indiction, Hebrew-Anno Mundi, Hijri-Islamic, Coptic, Ethiopian, Persian, Afghan-Pastu, Kurdish, Armenian, Baha’i, Indian Civil, Hindu Traditional, Chinese, Japanese, BS Nepali, Mayan. You can also find the Weekday, the Spring Equinox, the Summer Solstice, the Fall Equinox, the Winter Solstice, the Catholic Easter, the Orthodox Easter and the Julian Day Number. The additive value of this site concerns: (1) a reconstructed version of the ancient Attic (Athenian) Calendar, (2) the full format of the Armenian date corresponding to the current or any date with the ancient names of days and months along with the Christian feasts according to both the Apostolic Church and the Patriarchate of Jerusalem, (3) Full year calendars enriched with religious feasts for any selected year, in the frame of all the above-mentioned calendars and additionally the Old-Style Orthodox (Russian) Calendar, the Greek Orthodox Calendar, the Catholic Calendar, (4) Computation of Orthodox and Catholic Easter for any year, (5) Converting between Old-Style (Julian) and New-Style (Gregorian) Calendar, with the extra option of the Country and the Old-Calendarists case.
• Calendar Conversion, with options: Gregorian (New Style), Julian (Old Style), Weekday, Islamic (Moslem), Hebrew (Jewish), Mayan Long Count, Old Hindu Solar, Old Hindu Lunar, Achelis’ calendar, Coptic, Ethiopian, Jalali, Baha’i, Indian National Calendar, Revised Bengali, Revised Bengali, Japanese, Julian Day Number, Modified Julian Day Number, Lilian Day Number, Easter related days, Orthodox Easter related days.
• Calendar Converter (Fourmilab) (https://www.fourmilab.ch/documents/calendar/). Available fields: Gregorian Calendar, Julian Day, Julian Calendar, Hebrew Calendar, Islamic Calendar, Mayan Calendars, Indian Civil Calendar, French Republican Calendar, ISO Week –Day-Day of year, Unix time value, Excel Serial Day Number.

References

This article "Calendar Converter" is from Wikipedia. The list of its authors can be seen in its historical and/or the page Edithistory:Calendar Converter. Articles copied from Draft Namespace on Wikipedia could be seen on the Draft Namespace of Wikipedia and not main one.

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