Halo of the Cat's Eye

The Cat's Eye Nebula (NGC 6543) is one of the best known planetary nebulae
in the sky. Its haunting symmetries are seen in the very central region of
this stunning false-color picture, processed to reveal the enormous but
extremely faint halo of gaseous material, over three light-years across,
which surrounds the brighter, familiar planetary nebula. Made with data from
the Nordic Optical Telescope in the Canary Islands, the composite picture
shows emission from nitrogen atoms as red and oxygen atoms as green and blue
shades. Planetary nebulae have long been appreciated as a final phase in the
life of a sun-like star. Only much more recently however, have some
planetaries been found to have halos like this one, likely formed of material
shrugged off during earlier active episodes in the star's evolution.
While the planetary nebula phase is thought to last for around 10,000 years,
astronomers estimate the age of the outer filamentary portions of this halo
to be 50,000 to 90,000 years.