Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2012 October 4
Explanation: A mere seven hundred light years from Earth, in the constellation Aquarius, a sun-like star is dying. Its last few thousand years have produced the Helix Nebula (NGC 7293), a well studied and nearby example of a Planetary Nebula, typical of this final phase of stellar evolution. A total of 58 hours of exposure time have gone in to creating this deep view of the nebula. Accumulating narrow band data from emission lines of hydrogen atoms in red and and oxygen atoms in blue-green hues, it shows remarkable details of the Helix's brighter inner region, about 3 light-years across, but also follows fainter outer halo features that give the nebula a span of well over six light-years. The white dot at the Helix's centre is this Planetary Nebula's hot, central star. A simple looking nebula at first glance, the Helix is now understood to have a surprisingly complex geometry.
Authors & editors:
Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
A service of: ASD at NASA / GSFC
& Michigan Tech. U.