 On average, the astronomical solstices and the equinoxes advance by 10.8 minutes per year against the Julian year.As a result, the calculated date of Easter gradually moved out of alignment with the March equinox.While Hipparchus and presumably Sosigenes were aware of the discrepancy, although not of its correct value, it was evidently felt to be of little importance at the time of the Julian reform (46 BC).