NGC 40 is one of a class of objects called planetary nebulas, so-called because they look like the disk of a planet when viewed with a small telescope. This composite X-ray (blue)/optical (red) image of the nebula NGC 40 shows that it is a bubble of hot gas around a dying Sun-like star. In another 30,000 years or so, the nebula will dissipate, leaving behind a smallt, ultradense white dwarf star about the size of Earth.
Image Credit: X-ray—NASA / CXC / RIT / J.Kastner & R.Montez.; Optical—NSF / AURA / NOAO / WIYN