This spectacular summer constellation is unmistakeable, lying along the Milky Way, seemingly diving down towards the rich star fields of the heart of our galaxy. Looking at Cygnus, it is easy to see why it has the alternative appellation "The Northern Cross", as its six brightest stars do indeed form such a group. The celestial swan was placed in the sky by Zeus to honour the creature after he had transformed himself into one to enable him to seduce Leda, the queen of Sparta, thus fathering Castor and Pollux, the twins now called Gemini, and Helen of Troy and Clytemnestra, the wife of Agammenon.