“Heliacal” is based on the Greek “hēliakos,” from “hēlios,” meaning “sun.” The astronomical expression “heliacal rising” refers to a star or planet coming into view in the east before sunrise — the more common phrase is “morning star.” Prior to its heliacal rising phase, a star or planet has spent a season hidden behind the sun. In ancient Egypt, the heliacal rising of Sirius (the Dog Star) in the summer was an indicator the Nile would soon flood and nourish adjacent farmland, which began farming season. The English expression “the dog days of summer” refers to the idea that summer is at its hottest after Sirius’ heliacal rising.