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Chronology is a science of time measunnent in tenns of dates. days. months and years. Chronology has a historical backgroulld of well over ten thousand years. It involves the most important proh/em of firillg the commencing date of a calelldar(' ). In order to estimate periods of time. it is necessary to detennine starting date of the successive turns of the year.
Next in importance is to apply units of time-peliods for scielltific measunnent of actual passage of time in relation to the starting date of a calendar. For the purpose of fixing the commencement date a majoer
historical event is taken into consideration.
The Christian or A.D. Calendar begins from the date of birth of Jesus
Christ (May Gods peace be Upon him).from Islamic Hijri Calendar starts from the date of migration of the Holy Prophet Muhammad (May Allah:., Peace and Benediction be upon him) from Makkah to Madina. The Islamic Calendar is named Hijri Calendar, which had its Solar (or Irallian) and Lunar versions.
At present. Iranian, Islamic and Christian Calendars are available for obtaining whatever dates, days, months and years one may require from the calendars.
The writer of this article presents conversion tables prepared according to the relevant rules and formulas of Chronology based On the successive tums of the year and its months. The tables make it possible to obtain corresponding dates or days among the Hijri (Solar), and A.D. Calendars over a period of 169 years in the case of A.D. Calendar and 338 years for A.H. (Solar) Calendar.