As of today, May 21, the Sun enters the zodiac sign of Gemini.
Gemini, meaning "twins" in Latin, is represented by a couple of twins; namely, Castor and Pollux from Greek mythology, which referred to them jointly as the Dioskouroi (later to be known as Dioscuri in Latin), meaning "sons of Zeus". According to legend, however, only Pollux was the son of Zeus: the god, in fact, had visited the Queen of Sparta, Leda, disguising himself as a swan. The same night of their encounter, the Queen also laid with Tyndareus, her husband and King: as both unions were fruitful, she became pregnant with four children from two different fathers. Therefore, Castor and his sister Clytemnestra were fathered by Tyndareus, whereas Pollux and Helen (later to become famous ad Helen of Troy) were fathered by Zeus.
Castor and Pollux are also the names of the two brightest stars in the constellation, α Geminorum and β Geminorum respectively, which actually correspond to the heads of the two twins. Another constellation, Cygnus, seems to be linked to the same myth: its Latin name meaning "swan", Cygnus would in fact represent Zeus' disguise in order to seduce Leda.
"Gemini", illumination from a Book of Hours, Use of Rome, ms. G.14, f. 7v, 1470-1480, Morgan Library & Museum, New York.