Pope Gregory XIII

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Pope Gregory XIII Gender: M
Ugo Boncompagni
born on 7 January 1502 Jul.Cal. (17 Jan 1502 greg.) at 19:15 (= 7:15 PM )
Place Bologna, Italy, 44n29, 11e20
Timezone LMT m11e20 (is local mean time)
Data source
Date in question
Rodden Rating XX
Collector: Rodden
Astrology data s_su.18.gif s_capcol.18.gif 26°51' s_mo.18.gif s_capcol.18.gif 09°33 Asc.s_leocol.18.gif 25°42'

Pope Gregory XIII


Italian ecclesiastic, a Roman Catholic cardinal in 1565 and elected pope 13 May 1572. It was he who corrected the errors of the Julian calendar and introduced the calendar that bears his name.

Died 10 April 1585, Rome.

The Gregorian calendar

(copied from Wikipedia)

Pope Gregory XIII is best known for his reformation of the calendar, with the aid of Jesuit priest/astronomer Christopher Clavius, who is credited as the calendar's chief architect. The reason for the reform was that the average length of the year in the Julian calendar was too long - it treated each year as 365 days, 6 hours in length, whereas calculations showed that the actual mean length of a year is slightly less (365 days, 5 hours and 49 minutes) As a result, the date of the actual vernal equinox had slowly (over the course of 13 centuries) slipped to 10 March, while the computus (calculation) of the date of Easter still followed the traditional date of 21 March.

This was verified by the observations of Clavius, and the new calendar was instituted when Gregory decreed, by the papal bull Inter gravissimas of 24 February 1582, that the day after Thursday, 4 October 1582 would be not Friday, 5 October, but Friday, 15 October 1582. The new calendar duly replaced the Julian calendar, in use since 45 BC, and has since come into universal use. Because of Gregory's involvement, the reformed Julian calendar came to be known as the Gregorian calendar.

The switchover was bitterly opposed by much of the populace, who feared it was an attempt by landlords to cheat them out of a week and a half's rent. However, the Catholic countries of Spain, Portugal, Poland, and Italy complied. France, some states of the Dutch Republic and various Catholic states in Germany and Switzerland (both countries were religiously split) followed suit within a year or two, and Hungary followed in 1587.

However, more than a century passed before Protestant Europe accepted the new calendar. Denmark, the remaining states of the Dutch Republic, and the Protestant states of the Holy Roman Empire and Switzerland adopted the Gregorian reform in 1700-01. By this time, the calendar trailed the seasons by 11 days. Great Britain and its American colonies reformed in 1752, where Wednesday, 2 September 1752 was immediately followed by Thursday, 14 September 1752; they were joined by the last Protestant holdout, Sweden, on 1 March 1753.

The Gregorian calendar was not accepted in eastern christendom for several hundred years, and then only as the civil calendar.[2] The Gregorian Calendar was instituted in Russia by the Bolsheviks in 1917, Romania accepted it in 1919 under king Ferdinand of Romania (1 November 1919 became 14 November 1919), Turkey in 1923 under Ataturk, and the last Orthodox country to accept the calendar was Greece also in 1923.

While some Eastern Orthodox national churches have accepted the Gregorian calendar dates for feast days that occur on the same date every year, the dates of all movable feasts (such as Easter) are still calculated in the Eastern Orthodox churches by reference to the Julian calendar.

Link to Wikipedia biography


  • Work : New Job 1565 (Cardinal)
  • Work : Gain social status 13 May 1572 Jul.Cal. (23 May 1572 greg.) (Elected Pope Gregory XIII)
    chart Placidus Equal_H.
  • Death, Cause unspecified 10 April 1585 (greg.) in Rome (Age 82)
    chart Placidus Equal_H.

Source Notes

NN No.515. January 7, 1502 OS. Mercurio-3 No.10 gives 1815 GMT, speculative. Some sources give January 1; Book of Who has 6/07/1502


  • Lifestyle : Work : Same Job more than 10 yrs (12 years as pope)
  • Personal : Religion/Spirituality : Western (Christian, Roman Catholic)
  • Personal : Death : Long life more than 80 yrs (82 years)
  • Vocation : Religion : Ecclesiastics/ western
  • Vocation : Religion : Popes (Pope Gregory XIII)
  • Notable : Famous : Founder/ originator (Introduced Gregorian calendar)