99% Invisible

The Calendar

Apr 8, 2015
Explore the historical origins of the Gregorian calendar and its irregularities. Learn about the discovery of the true length of the year and the invention of leap year. Discover the history of calendar reform, including a radical 13-month calendar design. Understand the challenges faced in implementing a 13-month calendar and the significance of the calendar in different cultures.
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1
Introduction
00:00 • 2min
2
The Discovery of the Year's Length and the Julian Calendar
01:49 • 2min
3
The History and Reform of Calendars
03:27 • 4min
4
The 13-Month Calendar: George Eastman's Efforts and Challenges
07:50 • 6min
5
The History and Significance of the Calendar
14:03 • 3min