Heliacal Rising of Sirius

• The Heliacal Rising of Sirius is the first day that Sirius becomes visible again, rising in the east just before sunrise, after an absence of 70 days. Today, it rises in August.
• In the Ancient World, Sirius appeared just before the Summer Solstice in June, after a period of absence of 70 days. This return after an absence is called the Heliacal Rising of a star.

 Ancient Egypt

• During this Period of 70 days, Isis and Osiris passed through the Tuat or Underworld.
• As its Rising preceded the Annual Rise of the Nile, it was carefully observed by the Ancient Egyptians.
• The Calendar of the Middle Kingdom of Ancient Egypt was based on the first appearance of Sirius.

Heliacal Setting of Sirius

• The Romans celebrated the Heliacal setting of Sirius around April 25th, by sacrificing a Dog and a Sheep, to prevent their wheat crops from turning red with rust from the star.

The Six Red Stars

• Ptolemy (150 CE) describes Sirius as one of the six Red Stars, along with Aldebaran, Antares, Arcturus, Betelgeuse and Pollux.