The position of the ‘stars’ were integral to the days set aside as God’s days, for the feasts of Israel. I, for one, believe the prophecies concerning Messiah are marked by the feats days.
Position of the sun and moon were the main sign posts with adjustments periodically for the 360 day year as the seasons would fall out of line over 40 years or so(over 40 years=200 days). Psssover was set via special lunar stipulations yearly.