Why Did We Switch from Julian to Gregorian Calendars?

The Short Answer

Imagine you have a bicycle clock that gains one minute every day. After two years, it shows the wrong time! Long ago, people used a calendar called Julian to track seasons. It was close but not perfect. Over many hundreds of years, the calendar got too far ahead, and Easter happened in spring when it should have been late winter.

The Fix

In 1582, Pope Gregory XIII said, "Let us reset the clock!" He skipped some days so the seasons would line up correctly again. This new system is what we use today. It keeps our months in step with nature.