Watch closely. As this animation blinks between two Hubble Space Telescope images [
http://aries.usno.n…] of NGC 6543 - the first from 1994 and the second from 1997 - the intricate filaments of this nebula are seen to shift. The shift is due to the actual expansion of this gaseous shroud shed by a dying star [
http://oposite.stsc…]! NGC 6543 is more popularly [
http://oposite.stsc…] known as the Cat's Eye [
http://antwrp.gsfc.…] Nebula. Classified as [
http://www.seds.org…] a "planetary nebula", its complex, interwoven shells of expanding gas [
http://www.astro.wa…] have been castoff by the central star as it evolves from a red giant to its final white dwarf phase. The planetary nebula phase of a star's life is known to be relatively brief, lasting 10,000 years or so. In fact, combined with other data [
http://xxx.lanl.gov…], this nebula's detectable shift over a three year period allows the expansion age of its bright inner shells to be estimated at only around 1,000 years while its distance can be gauged at about 3,000 light-years.
Explanation
Watch closely. As this animation blinks between two Hubble Space Telescope images [
http://aries.usno.n…] of NGC 6543 - the first from 1994 and the second from 1997 - the intricate filaments of this nebula are seen to shift. The shift is due to the actual expansion of this gaseous shroud shed by a dying star [
http://oposite.stsc…]! NGC 6543 is more popularly [
http://oposite.stsc…] known as the Cat's Eye [
http://antwrp.gsfc.…] Nebula. Classified as [
http://www.seds.org…] a "planetary nebula", its complex, interwoven shells of expanding gas [
http://www.astro.wa…] have been castoff by the central star as it evolves from a red giant to its final white dwarf phase. The planetary nebula phase of a star's life is known to be relatively brief, lasting 10,000 years or so. In fact, combined with other data [
http://xxx.lanl.gov…], this nebula's detectable shift over a three year period allows the expansion age of its bright inner shells to be estimated at only around 1,000 years while its distance can be gauged at about 3,000 light-years.
Explanation
