Calendar Adjustment Day

Calendar Adjustment Day, observed annually on September 2, marks a significant moment in timekeeping history when New Year’s Day was officially moved to January 1. This day commemorates the adoption of the Gregorian calendar, which required omitting days to realign the calendar year with the astronomical year.

History

The switch to the Gregorian calendar in Britain was enacted by the British Calendar Act of 1751. As a result, after people went to sleep on September 2, 1752, they awoke on September 14, “losing” 11 days. This adjustment aimed to correct discrepancies between the calendar and the astronomical year, and it established January 1 as the new standard for New Year’s Day. The change caused public confusion and unrest, as traditional holidays, especially Easter, shifted to new dates. Historical documents from this era often differentiate dates as “Old Style” (Julian) or “New Style” (Gregorian).

Interesting Facts

• The Gregorian calendar was created primarily to improve the accuracy of predicting Easter’s date.
• Pope Gregory XIII did not personally design the calendar; it was developed by a commission including physician Aloysius Lilius and astronomer Christopher Clavius.
• The first printed Gregorian calendars appeared in 1582.
• Many Protestant communities initially resisted the new calendar, viewing it as a Catholic innovation.
• Astronomers sometimes use the Julian calendar for historical events to avoid confusion with dates before the Gregorian reform.

How to Take Part

Try using a printed desk calendar to enjoy the tactile experience of tracking time. Celebrate by marking meaningful dates and planning ahead. Explore historical dramas or documentaries that discuss the impact of losing 11 days, especially those relating to calendar reforms and timekeeping.

When is Calendar Adjustment Day in 2025?

Calendar Adjustment Day is observed on September 2 each year.

Observations