How could genealogical research be conducted without time and dates? After we have already explained the different calendrical systems in previous blog posts, in this article we would like to present the Julian calendar and the Gregorian calendar, the latter is valid today in Western countries.
The Julian calendar
Julius Caesar once assigned a mathematician and astronomer working out a solar calendar. In the year 45 BC the Julian calendar superseded the Roman lunar calendar. According to the Julian calendar, a new year began on 01 January instead on 01 March – the month names “September” (the Seventh) and “December” (the Tenth) still bear witness that a year and its months previously were counted in another way. The Julian calendar also brought a periodical leap year rule which was, however, incorrect and therefore modified under the reign of Augustus.
The Julian calendar also introduced new month names we still know today: The fifth month was renamed "iulius"in honor of Caesar; in honor of Augustus the month "sextilis" was renamed "augustus". Augustus is reputed to extend"his" month to 31 days (and shorten the February for this) in order to be in no way inferior to Caesar.
The Julian calendar included an inaccuracy between the calendrical year and the solar year, hence the Christian holidays shifted among other things. This, of course, displeased the Church. In 1582, Pope Gregory VIII enacted reforming the calendrical system - the Gregorian calendar arose.
The Gregorian calendar
With the Gregorian calendar, the leap year rule was reformed and the calculation of the Easter festival has been redefined among others.
Moreover, it is to mention that the date of the conversion from the Julian to the Gregorian calendar differed: in the Catholic parts of Germany, the Gregorian calendar was introduced already in 1583, but in the Protestant areas not until around 1700. Actually, in Russia and Greece the Gregorian calendar became valid in around 1920.
Conversion from Julian to Gregorian calendar
Due to the differences between the two calendar systems, the Julian calendar lags behind13 days. In order to convert a Julian date to the Gregorian calendar, these 13 days need to be added.
The Russian Orthodox Church actually still uses the Julian calendar and celebrates the Christmas Day on 7th January - which is 13 days after the Christmas Day inGregorian calendar (26 December).