Astronomy Picture of the Day

   [1]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.

                               2021 October 13
       [2]The picture shows a NGC 7822, known informally as the Cosmic
     Question Mark Nebula. Please see the explanation for more detailed
                                information.

                       NGC 7822: Cosmic Question Mark
                  Image Credit & Copyright: [3]Yizhou Zhang

   Explanation: It may look like a huge cosmic question mark, but the big
   question really is how does the bright gas and dark dust tell this
   nebula's history of [4]star formation. At the edge of a giant
   [5]molecular cloud toward the northern constellation Cepheus, the
   glowing star forming region NGC 7822 lies about 3,000 [6]light-years
   away. Within the nebula, bright edges and dark shapes stand out in this
   colorful and detailed skyscape. The 9-panel mosaic, taken over 28
   nights with a small telescope in Texas, includes data from
   [7]narrowband filters, mapping emission from atomic oxygen, hydrogen,
   and sulfur into blue, green, and red hues. The [8]emission line and
   color combination has become well-known as the [9]Hubble palette. The
   atomic emission is powered by [10]energetic radiation from the central
   hot stars. Their powerful winds and radiation sculpt and erode the
   denser pillar shapes and clear out a [11]characteristic cavity
   light-years across the center of the natal cloud. Stars could still be
   [12]forming inside the pillars by [13]gravitational collapse but as the
   pillars are eroded away, any forming stars will ultimately be cut off
   from their reservoir of [14]star stuff. This field of view [15]spans
   over 40 light-years across at the estimated distance of NGC 7822.

                       Tomorrow's picture: open space
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    Authors & editors: [27]Robert Nemiroff ([28]MTU) & [29]Jerry Bonnell
                                 ([30]UMCP)
          NASA Official: Phillip Newman [31]Specific rights apply.
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                A service of: [33]ASD at [34]NASA / [35]GSFC
                           & [36]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2110/NGC7822_Yizhou_4044.jpg
   3. https://www.astrobin.com/users/yzhzhang/
   4. https://science.nasa.gov/astrophysics/focus-areas/how-do-stars-form-and-evolve
   5. https://apod.nasa.gov/apod/ap201122.html
   6. https://spaceplace.nasa.gov/light-year/en/
   7. https://apod.nasa.gov/apod/ap060324.html
   8. https://en.wikipedia.org/wiki/Spectral_line
   9. https://hubblesite.org/contents/articles/the-meaning-of-light-and-color
  10. https://science.nasa.gov/ems/10_ultravioletwaves
  11. https://apod.nasa.gov/apod/ap150225.html
  12. https://hubblesite.org/science/stars-and-nebulas
  13. http://hyperphysics.phy-astr.gsu.edu/hbase/astro/gravc.html#c1
  14. https://www.universetoday.com/117494/what-does-it-mean-to-be-star-stuff/
  15. https://i.pinimg.com/originals/e9/5a/41/e95a41b46d7c2922ab0b3119e5ab6503.jpg
  16. https://apod.nasa.gov/apod/ap211012.html
  17. https://apod.nasa.gov/apod/archivepix.html
  18. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  19. https://apod.nasa.gov/apod/lib/aptree.html
  20. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  21. https://apod.nasa.gov/apod/calendar/allyears.html
  22. https://apod.nasa.gov/apod.rss
  23. https://apod.nasa.gov/apod/lib/edlinks.html
  24. https://apod.nasa.gov/apod/lib/about_apod.html
  25. http://asterisk.apod.com/discuss_apod.php?date=211013
  26. https://apod.nasa.gov/apod/ap211014.html
  27. http://www.phy.mtu.edu/faculty/Nemiroff.html
  28. http://www.phy.mtu.edu/
  29. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  30. http://www.astro.umd.edu/
  31. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  32. https://www.nasa.gov/about/highlights/HP_Privacy.html
  33. https://astrophysics.gsfc.nasa.gov/
  34. https://www.nasa.gov/
  35. https://www.nasa.gov/centers/goddard/
  36. http://www.mtu.edu/