A cycle of 1460 years in the calendar of ancient Egypt. The Egyptian calendar had a year of fixed length, 365 days, with no leap years. Consequently over one Sothic cycle the calendar regressed by one year with respect to the seasons, since the calendar year was approximately one quarter of a day shorter than the tropical year. The cycle takes its name from Sothis, the ancient Egyptian name for Sirius, whose heliacal rising marked the start of their year.