Eta

Its story

A massive blue star, seven times the Sun and nearly three thousand times more luminous, runs along the long serpentine body of the Water Snake at 587 light-years' distance. Its surface burns above 18,000 degrees; its rotation of around a hundred kilometres per second imprints a faint variable beat that for years left astronomers debating its classification. It is one of those hot, youthful beacons — barely 32 million years old — that pick out, with sharp precision, the serpentine geometry of the largest constellation in the sky.