Helix Nebula Hubble Space Telescope image of the Helix planetary nebula NGC This comprises shells of gas cast off a Sunlike star near the end of its life The colours are due to gases in the shells being ionised by radiation from the central star that ejected them The blue colour comes from oxygen and the red from hydrogen and nitrogen Despite its ring shape it is thought that the nebula is actually a cylinder aligned end on to Earth This is one of the nearest planetary nebulae to Earth lying light years away in the constellation Aquarius It is light years in diameter and appears half a Moonwidth wide
