Why did pope Gregory change the calendar?

Pope Gregory XIII introduced the Gregorian calendar in 1582 to correct inaccuracies in the Julian calendar, which miscalculated the solar year by about 11 minutes. This discrepancy caused the date of the spring equinox to drift over centuries, affecting the timing of important Christian feasts like Easter. The Gregorian reform aimed to realign the calendar with the seasons and the liturgical year, ensuring that these events occurred at their appropriate times. The new calendar was adopted gradually across different countries, leading to widespread acceptance today.