The Julian calendar based on the Roman calendar that had been in use for over 1500 years was not correct. In the Julian calendar a year was 365.25 days (365 days 6 hours) but should have been 365.2425 days (365 days 5 hours 49 minutes 12 seconds). The spring equinox occurs on/about March 21 but under the Julian calendar it had gradually moved back to on/about March 11. Since the date for Easter was dependent upon the equinox, it, too, was out of sync. Gregory dropped those ten days and moved the date back to March 21 and readjusted the calendar's leap years based on the new calculations. The reform was made in 1582 by Pope Gregory XIII.
Pope Gregory XIII revised the Julian calendar in 1582.
Pope Gregory XIII revised the Julian calendar to correct inaccuracies in timekeeping that had accumulated over centuries, leading to a misalignment between the calendar year and the solar year. This correction resulted in the adoption of the Gregorian calendar, which adjusted the leap year rules to better synchronize with the Earth's orbit around the sun.
The Gregorian calendar was initially decreed by Pope Gregory XIII on 24 February 1582.
The Gregorian calendar is named after Pope Gregory XIII, who introduced it in October 1582 to reform the Julian calendar. The Gregorian calendar is the most widely used calendar system in the world today.
Pope Gregory XIII in 1582.
Authorised by Pope Gregory
gregorian
Pope Gregory XIII
A calendar introduced by Julius Caesar in 45 BCE, which was later corrected by Pope Gregory XIII in the Gregorian Calendar.
The Gregorian calendar, named after Pope Gregory XIII, who rectified errors in the Julian calendar, which was the previously accepted calendar.
Pope Gregor XIII introduced the calendar named after him (the Gregorian calendar) in 1582. However, some countries adopted this calendar as late as the 20th. Century.
It is called the Gregorian calendar after Pope Gregory XIII and was introduced in 1582