The Sothic cycle or Canicular period is a period of 1461 ancient Egyptian years (of 365 days each) or 1460 Julian years (averaging 365.25 days each). During a Sothic cycle, the 365-day year loses enough time that the start of the year once again coincides with the heliacal rising of the star Sirius (called Sothis in Greek; a single year between heliacal risings of Sothis is a Sothic year). This rising occurred within a month or so of the beginning of the Nile flood, and was a matter of primary importance to this agricultural society. It is believed that Ancient Egyptians followed both a 365-day solar civil calendar and a lunar religious calendar.