Eta

Its story

Eta Serpentis is an orange subgiant lodged among the scales of the Serpent, barely sixty light-years away —a near neighbour on the Galactic scale. It weighs about one and a half solar masses and has swollen to nearly six times the Sun's radius, radiating some twenty times its energy. Its light, modest to the eye, has travelled only six decades: the generation looking up tonight is the very same one that was alive when the journey began.