*** THIS PICTURE MAY NOT BE USED TO STATE OR IMPLY NOAO ENDORSEMENT OF ANY COMPANY OR PRODUCT *** Abell 39 planetary nebula (blue), optical image. A planetary nebula (nothing to do with a planet) is a shell of gas and dust ejected from a star (centre) near the end of its life. Abell 39 has rare, near-perfect spherical symmetry, is about 5 light-years across, and its shell (white rim) is about a third of a light-year thick. The image is optically filtered to show oxygen ionization by radiation from the central white dwarf star. Abell 39 is 7000 light-years away in the constellation Hercules.