The Cat's Eye Nebula [ http://antwrp.gsfc.…] (NGC 6543) is one of the best known planetary nebulae in the sky [ http://antwrp.gsfc.…]. Its haunting symmetries [ http://www.cybercom…tiger.html ] 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 [ http://www.not.iac.…] in the Canary Islands, the composite picture shows emission from nitrogen atoms as red and oxygen atoms as green and blue shades. Planetary nebulae [ http://www.noao.edu…] have long been appreciated as a final phase in the life [ http://imagine.gsfc…stars.html ] of a sun-like star. Only much more recently however, have some planetaries been found to have halos [ http://www.ing.iac.…] like this one, likely formed of material shrugged off during earlier active episodes in the star's evolution. While the planetary nebula phase [ http://www.astro.wa…] 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.
