Civil time is occasionally adjusted by one second increments called leap seconds. A detailed explanation of what a second actually is, and why leap seconds are necessary. tycho.usno.navy.mil/leapsec.html
Extensive descriptions of many astronomical time keeping systems, with information on time zones and Julian day numbers. www.maa.mhn.de/Scholar/times.html
Lots of time and date related information, such as yearly and monthly calendars, counters, countdown, and the world clock which shows the current time in cities all over the world. www.timeanddate.com
The calendar was the center of Maya life and their greatest cultural achievement. To carry out their astronomical calculations they developed a sophisticated mathematical system. The Maya Calendar website is developing with the intent of providing a compl mayacalendar.com
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/cal_stud.htm
LunarCal is a 160-year perpetual Chinese Lunar Calendar for 1900 to 2060. Chinese festivals are listed and the moon phase is displayed. www.geocities.com/lunarcal
History and FAQs of calendars, from ancient Rome to outer space. Including Julian, Gregorian, Jewish, Islamic, Chinese, and Mayan. webexhibits.org/calendars
Lunar calendar with lunations, from new moon to new moon, instead of months. Moon phase on each day. Chinese, Jewish, and Islamic months. Eclipses, meteors, planets, star charts. Christian, Pagan, Islamic, Hindu, and Jewish holidays. www.pburch.net/lunarcal.html
Explanations of the Julian Calendar, the Gregorian Reform, the adoption of the Gregorian Calendar, the length of the tropical year and related matters. www.hermetic.ch/cal_stud/cal_art.html
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