Scientific Observation of Harmonic Drift in Lunar Dates against Gregorian calendar

Astronomy is one of earliest sciences that continued to evolve, through its application particularly in monitoring its evolving time. This has been proven as powerful tool in pegging important events in the evolution of human civilization. One of such phenomena is the lunar movement and it's implicating on lunar calendar, a template used by many countries around the world, notably Chinese, Jews and Muslim calendar. Observation shows that, dates in Islamic calendar, which are based on counting of days after first sighting of new crescent moon, at about 30 minutes after sunset, are mostly controversial. Considering the present advancement in science and technology, the controversy still persists and there is no available lunar calendar that is reliable for accurate longtime planning for Islamic activities. This resulted to lack of convincing Islamic calendar.Generally, observation that depends on naked eye sighting which has been widely used locally, cannot give reliable data for scientific analysis of lunar calendar because, the new crescent moon could be above western horizon after sunset, but due to obscurity impinged by weather or visual impairment, it may not be sighted. Therefore, for a true evaluation of lunar calendar, a scientific approach is adopted in order to determine possible first lunar location above western horizon at about 30 minutes after sunset, which is considered for reference location and time. This research shows that, the available lunar calendars are mainly drawn on the basis of numerical difference considered as the only drift before now, known as a consequence of the difference between the Islamic calendar and the Gregorian calendar. In this project, harmonic drift in lunar dates against the Gregorian calendar is noticed as a secondary drift and possible cause of the discrepancy in lunar calendar. The anomaly is in cooperated in developing the lunar calendar, thus aided the development of a reliable lunar calendar that could project dates for many years without showing any discrepancies.I hope that this book will be exciting to beneficiaries who include educational institutions and research centers, as well as individual enthusiasts of astronomy.