a blue object in the middle of a black sky

This planetary nebula is classified as Abell 39, and it’s one of the most uniform spherical shells amongst planetary nebulas that we’ve identified, with a shell estimated at approximately 2.8 light years in diameter. The nebula is estimated to be approximately 3,800 light years from Earth. The term “planetary nebula” is actually a misnomer, as this is an example of what happens to stars of one to eight solar masses after becoming red giants and losing their atmosphere, after which the core ionizes the ejected material. This star had a substantial component of oxygen which ionizes as blue. Our