Gregorian Calendar Reform

The Gregorian Calendar Reform was an adjustment made in 1582 to correct inaccuracies in the previous calendar system (the Julian calendar). The Julian calendar slightly miscalculated the length of the solar year, causing the date of the equinox to drift over time. To realign the calendar with the Earth's orbit, Pope Gregory XIII introduced the Gregorian calendar, which skipped 10 days in October 1582 and redefined leap year rules to improve long-term accuracy. This reform harmonized the calendar with the solar year, ensuring that calendar dates stay aligned with seasonal events such as solstices and equinoxes.