Planetary nebula. Hubble Space Telescope (HST) image of the planetary nebula NGC 2346. These clouds of gas are the outer layers of an old star which have been ejected near the end of its life. The central star here is actually a binary system in a very close mutual orbit. It is thought that the smaller star was swallowed as its partner expanded, causing a ring of gas to be ejected. The giant star's outer layers were then blown away, causing the formation of the two large lobes seen here. NGC 2346 lies around 2000 light years from Earth in the constellation Monoceros. It is around a third of a light year across.