Our Calendar

Most of the world now uses the Gregorian calendar, first introduced in 1582 by Pope Gregory XIII. But credit for the modern calendar should really be given to the Romans. The Gregorian calendar is based on the much earlier Julian calendar (which itself owed a lot to the Egyptian solar calendar), introduced by Julius Caesar in 45 BCE. The calendars share many similarities, though one of the main differences is the treatment of those pesky leap years. The Gregorian calendar handles them more precisely, resulting in a discrepancy between the two calendars that is currently 13 days, and will become 14 days in 2100.