Sothic cycle

The Sothic cycle is a period of 1,460 Egyptian years. This cycle represents the time it took for the Egyptian civil calendar, which had 365 days, to realign with the solar year. The Egyptian calendar would advance by one day every four years relative to the solar year. This meant that the start of the civil year would eventually drift through all the seasons before returning to its original position in relation to the sun.1

The ancient Egyptians named each year after significant events to help date documents. These year names evolved into annals that recorded historical and religious events. While these annals are lost, fragments and king lists, such as the Turin Papyrus, provide a framework for Egyptian chronology. Astronomical references, particularly the heliacal rising of Sirius (known as Sothis in Greek), were crucial for establishing precise dates. The heliacal rising of Sirius, the first visible appearance of the star on the eastern horizon before sunrise, marked the beginning of the Egyptian civil year. The coincidence of the civil new year with the heliacal rising of Sirius occurred approximately every 1,460 years, defining the Sothic cycle.234