 As you can see from these first two examples, planetary nebula are not about planets, they're about stars. It got the name planetary when early astronomers using small primitive telescopes first spotted these objects. They looked like disks similar to what they had seen when they looked at Jupiter and Neptune. Planetary nebula are actually stars like our sun that are going through a typical end of life cycle. They have ejected much of their mass into their surroundings and then collapsed in an explosion that ejects a massive amount of additional material at much higher velocities. The faster moving material crashes into the slower moving stuff to create spectacular formations. This helix nebula is just one of them. Here we have the fluorescing tube or a donut where we're looking straight down the middle of it. A forest of thousands of comet-like filaments embedded along the inner rim of the nebula point back towards the central star, which is a small, super-hot white dwarf. That's what's left. Each filament is around the size of our entire solar system. Based on the nebula's distance of 650 light-years, triangulating its angular size corresponds to a huge ring with a diameter of nearly 3 light-years. It would fill most of the space between our sun and our nearest star, Proxima Centauri.