Published by Australian Academy of Science
Useful sites | Calendars – keeping track of time

Calendars (University of Sydney Library)

Provides information on the history of calendars, an opportunity to make your own calendar, and links to perpetual, ecclesiastical, historical, and literary calendars. You can also search for world public holidays and festivals.
http://www.library.usyd.edu.au/subjects/readyref/calendars.html

The measurement of time (National Physics Laboratory, UK)

This site gives the definition of time and time scales (eg, calendars, the Earth's rotation, atomic time, the World time standard). It also answers the questions 'Why do we need accurate time?' and 'What are leap seconds and why do we need them?'
http://www.npl.co.uk/time/measurement_time/

How time works (How Stuff Works, USA)

Information about measuring time, time zones and daylight-saving time.
http://www.howstuffworks.com/time.htm

Time keeping (National Maritime Museum, Greenwich, UK)

Covers a number of topics relating to time. Of particular interest are 'Leap years' and 'The calendar'.
http://www.nmm.ac.uk/server.php?navId=00500300f00h

Calendars (Astronomy Department, New Mexico State University, USA)

By L.E. Doggett and reprinted from the Explanatory Supplement to the Astronomical Almanac, this article provides a detailed look at the Gregorian, Hebrew, Islamic, Indian, Chinese and Julian calendars.
http://astro.nmsu.edu/~lhuber/leaphist.html

The Golden Chain (Radio National, Australian Broadcasting Corporation)

Transcript from The Science Show (2 January 1999) on the history of astronomy. Ian Johnston, associate professor in the School of Physics at the University of Sydney, focuses on possible influences between astronomy and religion. Transcripts of the four subsequent programs in this series can be accessed through the site's index.
http://www.abc.net.au/rn/science/ss/stories/s19424.htm