The voluminous works of Islamic literature reveal minutest details of happenings and events related with life spam of Prophet of Islam, but I failed to find a reason why no serious effort was made in the past to confirm, or to ascertain most important dates in relation to life of Prophet, such as his date of birth or death; or, the starting point of Hijri calendar etc.
Recently I was asked by two gentlemen to explain, why there is no consensus among Muslim Ummah about even the dates of birth and death of Prophet (PBUH). It was a very genuine inquisition. Pick out any book or open the net, you would find different dates mentioned there, which is the cause of utter confusion. For a long time I had been collecting materials because I was planning to write a book on this subject. The above asked question proved to be enough stimuli to start writing this book.

After lapse of more than fourteen centuries, there seems no hope to confirmedly ascertain the said dates, unless we take help from astronomically collected data and then comparing the data with other calendars. Arithmetical Astronomy, as the name itself signifies, is a pure science, but due to some false notions developed in the past among general Muslims, a negative stigma had been attached to it, as this scientific subject had been considered to be one related with conjectural predictions for future. In Arabic, a single word “Nujoom’’ had been in vogue, which was considered to be connected with unknown (Ghaib), and as such its study was considered by Muslim as obnoxious or repugnant. In reality there are two different subjects, viz. Astronomy, and Astrology, for both of which Arabic or Persian word “Nujoom” is used, thus such aversion.
Astronomy is purely arithmetical science, without which solar or lunar eclipses cannot be calculated in advance; or, when rockets are sent to other planet, their exact positions in the wide cosmos cannot be calculated. While Astrology can be said to be what is being generally understood by “Nujoom”, as it is based on speculation or conjecture and to some extent Astrology may be attributed to the unknown, though that is also debatable. It is found written in records that this knowledge was revealed by God to one of his messengers, — prophet Idrees (AS).

In the Islamic scholarly treasure trove I found some of the astronomical data preserved though in a limited way, through which I tried to calculate the dates arithmetically based on well settled and accepted principles of Astronomical science.