Returning to the dying Castor, Pollux was given the choice by Zeus of spending all his time on Mount Olympus or giving half his immortality to his mortal brother. He opted for the latter, enabling the twins to alternate between Olympus and Hades. The brothers became the two brightest stars in the constellation Gemini (the twins): Castor (Alpha Geminorum) and Pollux (Beta Geminorum). As emblems of immortality and death, the Dioscuri, like Heracles, were said to have been initiated into the Eleusinian mysteries.