Annus Novus Decimal Calendar
A proposal for a non-sectarian, culturally neutral calendar system.
www.atlantium.org Details

Astro Portal - CalSKY
The worldwide interactive online astronomical/space calendar and calculator - for friends of astronomy, as well as astronomers.
www.calsky.com Details

Astronomical Time Keeping
Extensive descriptions of many astronomical time keeping systems, with information on time zones and Julian day numbers.
www.maa.mhn.de Details

Astronomy by JavaScript: Sun Calculators and More
Applets related to calendars and keeping time, including sidererial time.
www.jgiesen.de Details

Blue Moon Myths
Second full moon in a month, or third full moon in a single season?
www.infoplease.com Details

Britannica.com - Clockworks: From Sundials to the Atomic Second
Britannica.com explores the history of timekeeping, from sundials to cesium atomic clocks.
www.britannica.com Details

Calendar Studies
Articles on the Gregorian and Julian calendars, the ISO date format, the Julian day number system, the Maya calendar, the Goddess lunar calendar, the Liberalia Triday Calendar and C functions for date conversion; plus software for calendrical conversion.
hermetic.nofadz.com Details

Calendars through the Ages
History and FAQs of calendars, from ancient Rome to outer space. Including Julian, Gregorian, Jewish, Islamic, Chinese, and Mayan.
webexhibits.org Details

Calendrical Calculations
Published by Cambridge University Press. Gives a unified algorithmic presentation of the Gregorian, ISO, Julian, Coptic, Ethiopic, and Islamic civil calendars.
emr.cs.uiuc.edu Details