Planetary Nebula
An expanding shell of ionized gas ejected from a red giant star in the late stages of stellar evolution. Despite the name, it has no connection to planets. The glowing gas is illuminated by the hot core of the dying star.
Source: science.nasa.gov
APODs including "Planetary Nebula"
The Helix Nebula from CFHT
28/08/2000
One day our Sun may look like this. The Helix Nebula is the closest example of a planetary nebula created at the end of the life of a Sun-like star. The outer gasses of the star expelled into space appear from our vantage point as if we are looking down a helix. The remnant central stellar core, destined to become a white dwarf star, glows in light so energetic it causes the previously expelled gas to fluoresce. The Helix Nebula, given a technical designation of NGC 7293, lies 450 light-years away towards the constellation of Aquarius and spans 1.5 light-years. The above image was taken with the Canada-France-Hawaii Telescope (CFHT) located atop a dormant volcano in Hawaii, USA. A close-up of the inner edge of the Helix Nebula shows unusual gas knots of unknown origin.