its constellation, Canis Major (the Greater Dog). The heliacal rising of Sirius marked the flooding of the Nile in Ancient Egypt and the "dog days" of summer for the ancient Greeks, while to the Polynesians, mostly in the Southern Hemisphere, the star marked winter and was an important reference for their navigation around the Pacific Ocean. Observational history The brightest star seen from Earth, Sirius is recorded in some of the earliest astronomical records. Its displacement from the ecliptic causes its heliacal rising to be remarkably regular compared to other stars, with a period of almost exactly 365.25 days holding it constant relative to the solar year. This rising occurs at Cairo on 19 July (Julian), placing it just before the onset of the annual flooding of the Nile during antiquity. Owing to the flood's own irregularity, the extreme precision of the star's return made it important to the ancient Egyptians, who worshipped it as the goddess Sopdet (, "Triangle"; }, Sō̂this), guarantor of the fertility of their land. The ancient Greeks observed that the appearance of Sirius as the morning star heralded the hot and dry summer and feared that the star caused plants to wilt, men to weaken, and women to become aroused. Owing to its brightness, Sirius would have been seen to twinkle more in the unsettled weather conditions of early summer. To Greek observers, this signified emanations that caused its malignant influence. Anyone suffering its effects was said to be "star-struck" (, astrobólētos). It was described as "burning" or "flaming" in literature. The season following the star's reappearance came to be known as the "dog days". The inhabitants of the island of Ceos in the Aegean Sea would offer sacrifices to Sirius and Zeus to bring cooling breezes and would await the reappearance of the star in summer. If it rose clear, it would portend good fortune; if it was misty or faint then it foretold (or emanated) pestilence. Coins retrieved from the island from the 3rd century BC feature dogs or stars with emanating rays, highlighting Sirius's importance. The Romans celebrated the heliacal setting of Sirius around 25 April, sacrificing a dog, along with incense, wine, and a sheep, to the goddess Robigo so that the star's emanations would not cause wheat rust on wheat crops that year. Bright stars were important to the ancient Polynesians for navigation of the Pacific Ocean. They also served