that henceforth the two versions of the Great Year — the Platonic Great Year, defined by the planets, and the precessional, defined by the stars — were to be increasingly confused." Ptolemy has even been accused of committing scientific fraud by making up observations that would give the figure of 36,000 years even though the data available to him were good enough to get very near the true figure of 26,000. Josephus (first century AD) refers to a 'Great Year' () of 600 years. It has been suggested that he obtained this value from Berossos (c. 3rd century BC) who reckoned time in intervals of 60, 600 and 3600 years. Isaac Newton (1642 – 1726/27) determined the cause of precession and established the rate of precession at 1 degree per 72 years, very close to the best value measured today, thus demonstrating the magnitude of the error in the earlier value of 1 degree per century. See also () References Further reading Astronomical epochs History of astrology Astrological ages Precession