draconic months (4,630.53...). By comparing his own eclipse observations with Babylonian records from 345 years earlier, he could verify the accuracy of the various periods that the Chaldean astronomers used. The Hipparchic eclipse cycle is made up of 25 inex minus 21 saros periods. There are only three or four eclipses in a series of eclipses separated by Hipparchic cycles. For example, the solar eclipse of August 21, 2017 was preceded by one in 1672 and will be followed by one in 2362, but there are none before or after these. It corresponds to: 4,267 synodic months 4,630.531 draconic months 363.531 eclipse years (727 eclipse seasons) 4,573.002 anomalistic months References Ancient Greek astronomy Time in astronomy Calendars fr:Calendrier grec