|Osiris, god of the dead, was represented by the stars of the modern-day constellation Orion. Dead pharaohs supposedly became stars in Osiris as they joined the god. (UT Center for Middle Eastern Studies)|
Seth assumed the throne after he murdered Osiris and dumped his body into the Nile. But Isis, the consort of Osiris, recovered her husband's body and bore him a son Horus. Their son defeated Seth, and ruled the two kingdoms as the first pharoah of a united Egypt. Osiris became the god of the dead; Horus, the god of the sky.
In life, pharaohs were seen as the sons of Osiris. In death, they BECAME Osiris. They joined with the great god in the stars that honored him.
The original Osiris supposedly was buried in Abydos. Pilgrims from all across Egypt journeyed there for a festival in his honor. The festival was held in autumn, near the end of the Nile flood season. The floodwaters brought rich soil that kept the valley fertile. At the same time, the stars that represented Osiris were "resurrected" in the eastern sky just before sunrise. The renewal of both heaven and Earth was a potent symbol that reaffirmed the power of Osiris and the religion that honored him.