Without hardly a thought to the calendar itself, we begin another year. Yet the development of the calendar was a major advance, based on astronomy as well as religion. The Gregorian calendar we use today was created in the 1580's by Pope Gregory XIII. Want to learn more? Start your new year here. [Editor's Note: An updated version of this topic can be found here: History of the Calendar]
The Aztec Indians of the fifteenth and sixteenth century had one of the most advanced civilizations in the Americas. Although they were destroyed by the conquering Spaniards in 1521, they left a lasting mark on Mexican culture. The Aztec used two independent calendars. The xiuhpohualli was a solar calendar that described the days and rituals related to the seasons. It had 365 days. The tonalpohualli, or day count, was a sacred calendar with 260 days. Its purpose was to divide the days among the various gods.
"In the 1840's a Greenwich standard time for all of England, Scotland, and Wales was established, replacing several 'local time' systems. The Royal Greenwich Observatory was the focal point for this development because it had played such a key role in marine navigation based upon accurate timekeeping. Greenwich Mean Time (GMT) subsequently evolved as the official time reference for the world and served that purpose until 1972." This fabulous site, produced by the National Institute of Standards and Technology, presents both the history of timekeeping and a peek at its current state. If you want to coordinate your Windows-based computer clock to the NIST clock, you can download a program to do so over the Internet.