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by Rodion Herrera, Astronomical Solutions Company L.L.C
The sighting of the new moon is a particular subject in astronomy that has fascinated many observers since prehistory. Evidence of early human civilizations using the moon as a basis to measure time in the form of an actual lunar calendar has been discovered in the ancient plains of Scotland, dating back to 8,000 B.C. Professor Samuel L. Macey of the International Society for the Study of Time in his book, Encyclopedia of Time, says that using the moon to measure the passage of seasons was evident as far back as 28,000-30,000 thousand years. Therefore, the method by which we measure the beginning and the end of the new moon phase is indeed a crucial part of determining the accuracy of any lunar calendar.

Since the Islamic months follow a lunar calendar, the start of each month is marked by the first sighting of the crescent moon. It is important to note however, that the Islamic new moon is actually different to the βastronomical new moonβ. We define the astronomical new moon as that point when it is in conjunction with the sun, and thus it is actually too close to the sun and is very dark, for most of the lunar disc is in shadow. This point marks the beginning of measurement for the true age of the moon.
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