The Dioscuri were the star-crowned, twin gods of St. Elmo’s fire, an electrical discharge which appears on the rigging of ships portending deliverance from a storm. They were also gods of horsemanship and protectors of guests and travellers.
Residence: Mount Olympus/Underworld
Parents: Leda, Zeus and Tyndareus
Consorts: Hilaeira and Phoebe
Roman equivalent: Castor and Pollux
The twins were born as mortal princes, sons of the Spartan queen Leda but they had different fathers; Castor was the mortal son of Tyndareus, the king of Sparta, while Polydeuces was the divine son of Zeus, who seduced Leda in the guise of a swan. Because of their kindness and generosity they were apotheosised at death. Polydeuces, being a son of Zeus, was at first the only one offered this gift but he insisted it be shared with his twin Castor. Zeus agreed, but in order to appease the Fates, the twins had to spend alternate days in heaven and the underworld.
The Dioscuri were also placed amongst the stars as the constellation Gemini (the Twins). The division of their time between heaven and the underworld might be a reference to the heavenly cycles, for their constellation is visible in the sky for only six months of the year.