The Julian Calendar was introduced by Julius Caesar in 46 BC as a reform of the Roman calendar. It was based on a solar year of 365.25 days, with an extra day added every four years to account for the extra quarter day. However, this system led to a slight overestimation of the solar year, resulting in a discrepancy of about 11 minutes annually.
As a result, over the centuries, the Julian Calendar fell out of sync with the seasons, leading to the need for a more accurate calendar system.
Julian Calendar Gregorian Calendar Difference
The Adoption of the Gregorian Calendar
In 1582, Pope Gregory XIII introduced the Gregorian Calendar as a refinement of the Julian Calendar. The Gregorian Calendar addressed the inaccuracies of its predecessor by eliminating the leap year in years ending in “00” unless divisible by 400. This adjustment helped bring the calendar back in alignment with the solar year, reducing the annual discrepancy to just 26 seconds.
The Gregorian Calendar was widely adopted by Catholic countries at the time, with Protestant and Orthodox countries gradually following suit over the next few centuries.
Key Differences Between the Julian and Gregorian Calendars
One of the major differences between the Julian and Gregorian Calendars is the leap year rule. While the Julian Calendar adds a leap day every four years, the Gregorian Calendar skips the leap year in century years unless divisible by 400.
Another significant difference is the date of the New Year. The Julian Calendar starts the New Year on January 1st, while the Gregorian Calendar shifted the start of the year to January 1st from March 25th.