A planetary nebula is actually nothing to do with planets. It is formed when a star of low or intermediate mass approaches the end of its life, with most of the star's mass blown out in a roughly globular shape. In early telescopes, these often blue shapes looked like the round shapes of giant planets like Uranus.
This photo was by Jovan Kulic:
Still working my way through the big ones.
Helix Nebula NGC 7293.
Ha 7 x 20 minutes RGB 6 x 10 minutes each
Williams Optics GTF 81 mm
Focal Ratio F5.9
Losmandy G11 mount
Atik 320e mono camera
Baader Ha 7nm, R, G, B filters
Compare it to this one, taken using a 2.2 metre Max Planck Society/ESO telescope at La Silla in Chile, and you realise just how good Jovan's photo is: