Sunday, January 2, 2011

Babylonians again

If you ever took an astronomy class and paid attention, you know that there are two different ways of defining a month:  sidereal month and synodic month.  Frankly, these tax my retention.  But the real picture is even more complicated.

Shlomo Sternberg, Celestial Mechanics (1969), p. 26:

The return [of the moon] to maximum velocity  takes slightly longer than a sidereal month, and slightly less than a synodic month.  The period of return to maximum velocity is known as the anomalistic period or anomalistic month.

Thus far, a curiosity of astronomy;  one which, one might venture at hazard, was discovered by some persistent fellow with a telescope, prior to the discoveries of quasars or the Red Shift, but probably not all that long before.

But no.   The facts were known in the second century B.C.E. -- and this, in dizzying detail:

Hipparchus gives the relation that 251 synodic periods  are almost exactly equal to 269 anomalistic periods.

Now, at this point, things become seriously weird:

What is most striking is that we find this ratio 251/269 used in a theoretical way in Babylonian tables.

            This startlingly early anticipation does not mean that the ancient Babylonians had been informed of the facts by visiting Space Aliens, as the New Agers would no doubt have it (if they have heard of this story at all).  But it does suggest a preternaturally diligent interest in astronomical niceties.
            And indeed, preternatural is here the operative word.  For as Sternberg several times mentions, the desire for extraordinarily precise knowledge of the celestial facts  stemmed, among the ancient Hebrews, from necessities of religious observance.   Islam likewise has such requirements, a fact perhaps not unconnected with another blazingly insightful observation of the late 9th/early 10th century (p. 20):

The motion of the apogee (beyond the effect due to precession) was apparently first discovered by the Arabian astronomer al-Battani.

These, then, are instances in which religion was the midwife of science.  Other instances are familiar from the field of linguistics, where the preservation and explication of sacred Scripture (the Vedas, the Bible, the Koran) was the motivation.

No comments:

Post a Comment