Astronomy Picture of the Day

                         Astronomy Picture of the Day

    Discover the cosmos! [1] Each day a different image or photograph of our
 fascinating universe is featured, along with a brief explanation written by a
                           professional astronomer.

                                2018 October 20
                                      [2]
                            Halo of the Cat's Eye
 Image Credit & Copyright [3] : Data: Michael Joner (West Mountain Observatory
    [4] , BYU), Romano Corradi [5]  (IAC [6] ), Hubble Legacy Archive [7]  -
                        Processing: Robert Gendler [8]

Explanation: Not a Falcon 9 [9] rocket launch after sunset, the Cat's Eye
Nebula (NGC 6543) is one of the best known planetary nebulae in the sky. Its
haunting symmetries [10]  are seen in the very central region of this
composited picture [11] , processed to reveal an enormous but extremely faint
halo of gaseous material, over three light-years across. Made with data from
ground- and space-based telescopes it shows the extended emission which
surrounds the brighter, familiar planetary nebula [12] . Planetary nebulae
have long been appreciated as a final phase in the life [13]  of a sun-like
star. But only more recently have some planetaries been found to have halos
[14] 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 outer
filamentary portions [15]  of this halo to be 50,000 to 90,000 years old.

                  Tomorrow's picture: meteor, comet, nebula

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Site notes:
  [1] archivepix.html
  [2] image/1810/NGC6543-BYU-L.jpg
  [3] lib/about_apod.html#srapply
  [4] http://wmo.byu.edu/
  [5] http://vivaldi.ll.iac.es/galeria/rcorradi/
  [6] http://www.iac.es/
  [7] http://hla.stsci.edu/
  [8] http://www.robgendlerastropics.com/
  [9] ap181012.html
  [10] ap080804.html
  [11] http://www.robgendlerastropics.com/NGC6543-BY...
  [12] http://en.wikipedia.org/wiki/Planetary_nebula
  [13] https://imagine.gsfc.nasa.gov/educators/lifec...
  [14] ap140522.html
  [15] http://www.youtube.com/watch?v=tw0VJ1K93PM
  [16] ap181019.html
  [17] archivepix.html
  [18] lib/apsubmit2015.html
  [19] lib/aptree.html
  [20] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apo...
  [21] calendar/allyears.html
  [22] /apod.rss
  [23] lib/edlinks.html
  [24] lib/about_apod.html
  [25] http://asterisk.apod.com/discuss_apod.php?dat...
  [26] ap181021.html
  [27] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [28] http://www.phy.mtu.edu/
  [29] https://antwrp.gsfc.nasa.gov/htmltest/jbonnel...
  [30] http://www.astro.umd.edu/
  [31] lib/about_apod.html#srapply
  [32] https://www.nasa.gov/about/highlights/HP_Priv...
  [33] https://astrophysics.gsfc.nasa.gov/
  [34] https://www.nasa.gov/
  [35] https://www.nasa.gov/centers/goddard/
  [36] http://www.mtu.edu/

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