Measuring time has always been an important trait of human civilization evolved constantly; from Mayan pyramids to Gregorian calendar, Middle-earth calendar or Stardates, it all has been quest of time keeping. Calendars can be divided into three major categories; Solar, Lunar and Fiscal. A detailed list of calendars can be found here.
Gregorian Calendar is a modification of Julian Calendar, a fix to be precise. Some details from wikipedia, the free encyclopedia:
It was first proposed by Neapolitan doctor Aloysius Lilius, and was decreed by Pope Gregory XIII, for whom it was named, on February 24, 1582 (Note: The papal bull Inter gravissimas was dated 1581, as the year was at that time taken to commence in March). The Gregorian calendar was devised because the mean year in the Julian Calendar was a little too long, causing the Vernal equinox to slowly drift earlier in the calendar year.
The Hijri calendar is a lunar calendar recognizes one era: A.H. (Latin "Anno Hegirae", which means "the year of the migration," in reference to the migration of Muhammad (Peace be upon him) from Mecca. In contrast to this, Hebrew calendar is a lunisolar calendar i.e. a lunar calendar with solar cycles.
I wanted to rant more on .NET framework classes, globalization and calendars but I think we are leaving to see Marina Del Ray new year’s fireworks. So, Happy New Gregorian Year and Good Bye 2004! Don’t forget to remember tsunami victims in your New Year prayers and resolutions.
Iranian calendar (Solar Islamic Calendar)
http://en.wikipedia.org/wiki/Iranian_calendar
Bahá'í calendar
http://en.wikipedia.org/wiki/Bah%E1%27%ED_calendar
DMOZ Calendars and Timekeeping category: http://dmoz.org/Science/Astronomy/Calendars_and_Timekeeping/
HijriCalendar Class
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemglobalizationhijricalendarclasstopic.asp
HijriCalendar.GetEra Method
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfSystemGlobalizationHijriCalendarClassGetEraTopic.asp
HebrewCalendar.GetEra Method
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfSystemGlobalizationHebrewCalendarClassGetEraTopic.asp
