Historical Background to Astronomy

Abstract

The genealogy of modern astronomy is traceable back to the records of celestial events deciphered by archeologists working on the site of ancient Mesopotamia [1], so named by the Greeks because it lies between the two great rivers: the Tigris and the Euphrates, in what is now Iraq. These records consist of wedge-shaped cuneiform characters imprinted on clay tablets, the earliest of which date back to the third millennium bc. The Mesopotamians could not have chosen a more durable medium. Their number system is sexagesimal, that is, it is a place-value system with base 60; however, the representation of the numbers 0,1,2,…..59 is reminiscent of the Roman numerals in that these numbers are constructed by repetitions in just two distinct cuneiform characters: one vertical and the other horizontal, as shown in Fig. 3.1. They lacked a symbol for zero (whose origin is thought to be Indian) so the presence of a zero is shown simply by an empty space. Our division of hours into 60 min and minutes into 60 s, with similar base 60 divisions of degrees of arc into minutes and seconds of arc, is undoubtedly of Babylonian origin [2].