“The context in Censorinus shows that the interval of 2434 years was in Aristarchus’s opinion the interval between alternate conflagrations and inundations of the world when the sun, moon, and stars all return to the same zodiacal sign.
It is very difficult to trace exactly the adoption of Babylonian ideas by the Greek astronomers. An active part in the diffusion of Babylonian astronomy is often ascribed to Berosus the Chaldaean, who was a contemporary of Aristarchus, and had a doctrine of cataclysms similar to his; for Berosus claimed that when all the planets were in Cancer the earth would be burned, and when they were in Capricorn there would be a flood.
But an examination of the astronomical fragments of Berosus suggests that he had a very inadequate knowledge of the subject. His views on the moon’s phases are reported by Vitruvius, who contrasts them with the explanation given by Aristarchus.
It looks indeed as though Aristarchus set out deliberately to refute the views of his Babylonian contemporary, who settled in Cos, not far from Samos, the home of Aristarchus. Berosus supposed that the moon had light of her own, one half of her orb being luminous and the rest of a blue colour. The moon’s phases thus in his view were caused by her luminous half being turned towards or away from the earth.
Aristarchus, however, maintained that the moon receives her light from the sun, so that on the fourteenth day of the month when she is in opposition to the sun, she is full and rises when the sun is setting.
Vitruvius shows that Aristarchus explained the first and last quarters and the new moons as well; and it is obvious from Aristarchus’s book on the sizes and distances of the sun and moon that Berosus had nothing to teach the Samian about the phases of the moon.
No doubt Aristarchus applied what he had learned from Strato and his own theory about light and shadow to the moon’s phases and to eclipses also. The most obvious objection to Berosus’s doctrine was that it failed to explain lunar eclipses, as Cleomedes [2.4] pointed out.
It is most unlikely that Berosus had anything worth while to teach the Greeks about theoretical astronomy, though he did have a cursory interest in the subject, having treated it in the first book of the Babyloniaca (P. Schnabel, Berossos und die babylonisch-hellenistische Literatur, Leipzig 1923, p. 19.)
We are told also that he maintained that Babylonian astronomical records did not go back before the time of Nabonasar, that king having destroyed the earlier ones. In view of this clear statement it is surprising to find that according to our texts of Pliny, Berosus held that observations of the stars had been inscribed on baked tablets for 480,000 (!) years (490,000 in some copies).
If we read CCCCLXXX for CCCCLXXX we can reduce the period to 480 years. Now Berosus dedicated his Babyloniaca to Antiochus I Soter, who reigned from 281/0 to 262/1 B.C., and if we add 480 to a year in the reign of that king we are brought close to the epoch of Nabonasar.
I think it likely therefore that Berosus stated that accurate observations had been made in Babylonia for 480 years from the time of Nabonasar, and that earlier observations were not available to him. This suggestion is supported by the failure of Ptolemy in the Almagest to cite any Chaldaean observations earlier than the time of Nabonasar.
If Ptolemy’s dating of the first year of Nabonasar to 747 B.C. was the same as Berosus’s, then we have a date for the publication of the Babyloniaca, 480 years after 747 B.C. or 267 B.C., a year well within the reign of Antiochus I to whom the work was dedicated.”
George Huxley, “Aristarchus of Samos and Graeco-Babylonian Astronomy,” Greek, Roman and Byzantine Studies, Duke University, Vol 5, No 2 (1964), pp. 125-7.