The legend concerning the twins Castor and Pollux is very weird. Zeus fell in love with Leda, the wife of Tindaro, king of Sparta, and made love to her in the form of a swan, after which she laid two eggs, in the vicinity of Sparta. One of the two gave birth to the twins Pollux and Helen. The second egg procreated Castor and Clytemnestra who, however, were sons of Tindaro, who made love to Leda after her intercourse with Zeus. Therefore Pollux, being the god's son, was immortal, while his "human." brother was not. They were Spartan heroes par excellence, Pollux being an unbeatable boxer, while Castor was a fearless warrior.
They fought against the Athenian Theseus, helped Jason on several occasions, and participated in the expedition of the Argonauts. Since they had subdued a storm on that occasion, they were considered the protectors of sailors. According to one version of the legend, during the wedding of Leucippus' daughters, the twins kidnapped the two girls. In the fight that ensued, Castor was killed and descended into the underworld. Pollux, wounded, was taken to heaven by Zeus but, not wanting to be separated from his beloved brother, asked Zeus to release him from immortality, so as to be able to reach Castor. Zeus was moved by their mutual attachment and allowed them to stay together, one day in the underworld and one day among the gods. Afterwards, as a reward for their brotherly love, they were both placed in heaven as a constellation.
The Twins are seen in April in the west, at approximately 10 p.m. The constellation occupies 514 square degrees, and borderes Auriga and Lynx to the north, Taurus and Orion to the west, Unicorn and Canis Minor to the south, and Cancer to the east. Since it is crossed by the Milky Way, it contains many galactic bodies. In Gemini the Sun reaches the summer solstice.