NGC 6543 Halo of the Cat's Eye. The Cat's Eye Nebula is one of the best known planetary nebulae in the sky. Its symmetries are seen in the very central region of this false-color picture, pro-cessed to reveal the enormous but extremely faint halo of gaseous mater-ial, over 3 ly across, which surrounds the brighter, familiar planetary nebula. Made with data from the Nordic Optical Telescope, Canary Islands.