Gregorian calendar

The Gregorian calendar is the calendar widely used in the Western world. A modification of the Julian calendar, it was first proposed by the Neapolitan doctor Aloysius Lilius, and was decreed by Pope Gregory XIII, for whom it was named, on 24 February 1582 (Note: The papal bull Inter gravissimas was signed in the year 1581 for unknown reasons, but printed on 1 March in 1582. Although 1581 is often attributed to the use of years beginning on 25 March by the papacy, other contemporaneous papal bulls have years that do not agree with March years, let alone years since a pope was named or other types of years.)

External links

• Inter Gravissimas, Gregory XIII's bull introducing the new calendar (Latin and French)
• Inter Gravissimas (Latin and French plus English)
• British Calendar Act 1751
• Frequently Asked Questions about Calendars
• The Perpetual Calendar Gregorian Calendar adoption dates for many countries.
• Synoptical Julian - Gregorian calendar Compare Old and New Style dates 1582 - 2100.