December 15

Calendar and seasonal context

The day number depends on whether the year is a leap year. In leap years one additional day, February 29, shifts the ordinal count by one; for more about how leap years are determined see leap years. December 15 often occurs during the period when the Geminids meteor shower is active, which peaks around mid-December.

Notable observances and events

One widely observed event on December 15 in the United States is Bill of Rights Day, commemorating the ratification of the first ten amendments to the U.S. Constitution on December 15, 1791. Beyond that national observance, the date can host religious feast days, local festivals and other commemorative events that vary by country and culture.

Historical and cultural notes

A number of historically significant births and events have occurred on this date. For example, the French civil engineer Gustave Eiffel was born on December 15, 1832. Across centuries, December 15 has been the setting for political decisions, cultural milestones and scientific achievements; specific items differ by year and region.

Why the date matters

Dates such as December 15 are useful reference points for chronology and commemoration. They help societies mark anniversaries, organize holiday seasons and anchor seasonal activities. Astronomical events, historical anniversaries and civic observances all contribute to the day's contemporary significance.

Quick facts

• Day of year: 349 (350 in leap years)
• Days remaining in year: 16
• Common associations: Bill of Rights Day (U.S.), mid-December meteor activity, winter season in the Northern Hemisphere

For further reading on the calendar systems and how days are counted across years and leap-year cycles, see general references on the Gregorian calendar and explanations of leap years.