Calendars and Timekeeping

Astronomical Time Keeping

Features article on the process of determining astronomical time such as sidereal, solar, ephemeris and atomic.

Astronomy Center - The Old Farmer's Almanac

Provides a skywatch, tide predictions, forums and links.

Cal Sky

Features the most accomplished astronomical observation and online-calculator of the planet.

Calendar, Leap Years and the Year 2000 AD

Shows article on the history and types of calendar. Also contains definitions of the day, week, month and year.

Earth Orbit

Information about the solstices, equinoxes, and seasons from Eric Weisstein's Treasure Trove of Astronomy.

Greenwich Mean Time

Contains data on different time, season and time zones of different continents and countries.

Length of Day and Twilight (Formulas)

Derives the formulae needed to calculate the length of the day, based on day of year and latitude

Mathematics of the Chinese Calendar

Features a research paper on the Chinese calendar by Helmer Aslaksen. Shows photos and diagrams.

NASA Eclipse Web Site

Dates of solar and lunar eclipses.

Paula Burch

Features article on lunisolar calendar of 2006. Also shows diagram of the calendar.

Physics and Astronomy

Contains scripts for calculating solar information such as sunrise, sunset, twilight, altitude and azimuth.

Time and Date

Discusses the difference between the Millennium and year 2000. Also shows charts of staring dates for centuries and millennia.

Time to Talk

Features article on Blue Moon by Borgna Brunner and Anne Marie Imbornoni. Also contain information on its kinds and calculations as to when it happens.

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