Sothic Cycle

Sirius (bottom) and Orion (right). The Winter Triangle is formed from the three brightest stars in the northern winter sky: Sirius, Betelgeuse (top right), and Procyon (top left).

The Sothic cycle or Canicular period is a period of 1,461 Egyptian civil years of 365 days each or 1,460 Julian years averaging 365¼ days each. During a Sothic cycle, the 365 day year loses enough time that the start of its year once again coincides with the heliacal rising of the star Sirius (Ancient Egyptian: Spdt or Sopdet, 'Triangle'; Greek: Σῶθις, Sō̂this) on 19 July in the Julian calendar.

It is an important aspect of Egyptology, particularly with regard to reconstructions of the Egyptian calendar and its history. Astronomical records of this displacement may have been responsible for the later establishment of the more accurate Julian and Alexandrian calendars.

See Also

Heliacal rising