The brightest star in the night sky is Seirios (Sirius) in the constellation Canis, and it is traditionally associated with the Dog Days, when there is hot weather. During the Dog Days from late July to late August, Sirius in Southern Europe is visible shortly before sunrise. The brightness and its blue hue from the star was believed to produce a “side-effect” which could bring on deadly epidemic diseases. Hesiod and Homer mention that the Dog Star was believed to have brought on diseases associated with the over-heating and drying of the body, such as fevers. Seirios held particular importance at Keos, a bright clear appearance of the star portended good fortune, while a faint appearance signaled pestilence. At Keos there was cult where inhabitants try to guard against the effects of the Dog Star using rituals. The Dog Star was burning the Cyclades with its heat and producing much pestilence on the islands and therefore the people of Keos prayed to the rural god Aristaios, the son of Apollo and Kyrene, who was taught both medicine and divination by the Centaur Chiron. Aristaios came to the island from Libya where he was born, built an altar to the god Zeus, who then relieved the suffering of the Keians by bringing refreshing winds and rains. Aristaios ordered the islanders to perform this rite every year so as to appease the violent rising of the Dog Star and to pray to Zeus for the Etesian winds. A coin from Keos showing the dog star on the reverse: Cyclades, Keos. Karthaia. AE. Late 3rd-early 2nd century B.C. Obverse: Laureate head of Apollo to right. Reverse: Forepart of a dog (Seirios) to left; below, fly; all within circle of rays. Reference: Papageorgiadou-Banis Series VIII, Issue 1. SNG Copenhagen 623-624. 3.93g; 16mm Ex Tom Cederlind Estate, previously from Frank L. Kovacs (San Rafael, CA, USA) and Hellenic Roman Coins (Hewitt, NJ). The citizens of Keos watched for the rising of the Dog Star every year from the mountaintops. By observing the appearance of the star the inhabitants would try to determine whether the island would suffer from epidemics or not. If the star appeared clear and bright, the islanders would experience a healthy year, but if it appeared misty and dull, disease would spread across the island. Aristaios did not stay on Keos but traveled the western Mediterranean Sea, visiting the islands there and for a time even ruling over Sardinia. Later still he traveled to Thrace where he lived near Mt. Haimos and became initiated in the rites of Dionysos. A coin from Keos with Dionysiac iconography associated to Aristaios: Cyclades, Keos. Karthaia. late 4th-early 3rd century BC. AE. Obverse: Youthful head of Dionysos to right, wearing ivy wreath. Reverse: [ΚΑΡΘΑ] Grape bunch; in left field, the dog-star, Sirius. Reference: HGC 6, 555. Joy 522-3. Papageorgiadou-Banis Group VII issue 2. 5.35g; 19mm From the Vineyard Collection, ex Classical Numismatic Group 60, 22 May 2002, 592. Ex Münzen & Medaillen GmbH Auktion 5, 21 October 1999, 193. Please share your coins of the Cyclades, coins featuring a star or a dog and coins with Dionysiac iconography!