When Was The Modern Calendar Invented

The Gregorian calendar is the calendar used in most of the world. An attempt to reform the calendar to include a leap year was made at the beginning of the Ptolemaic dynasty Decree of Canopus 239 BCE but the priesthood was too conservative to allow such a change. This corresponded closely to the true solar year being only 12 minutes shorter. The calendar spaces leap years to make its average year.

Gregorian Calendar Wikipedia

The most widely used calendar around the world today is called the Gregorian calendar.

When Was The Modern Calendar Invented. It was introduced in October 1582 by Pope Gregory XIII as a minor modification of the Julian calendar reducing the average year from 36525 days to 3652425 days and adjusting for the drift in the tropical or solar year that the inaccuracy had caused during the intervening centuries. As a result as Sen put it he invented a combined calendar which paralleled his interest in floating a combined religion the Din-e-Ilahi. The ancient Egyptians originally employed a calendar based upon the Moon and like many peoples throughout the world they regulated their lunar calendar by means of the guidance of a sidereal calendar.

Prior to that the year was not standardised throughout the world. But Gregory XIII only approved the calendar that bears his name. The actual inventor was Alosyius Lilius.

It was introduced by Pope Gregory XIII in the 16th century CE and was a modification of an ancient Roman calendar called the Julian calendar. I believe this was introduced with the Gregorian calendar by Pope Gregory XIII in the 16th century. This calendar modestly titled the Tarikh-e-Ilahi.

The Leap Year in Ancient Egypt. This pre-dates the Julian reform of 46 BCE which Julius Caesar introduced on the advice of the Alexandrian astronomer Sosigenese. This new calendar called the Tarikh-e-Ilahi or the calendar of God was started in 1584 AD the Scroll article said.

History Of Calendars Wikipedia