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.

                               2022 January 27
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                               South of Orion
                Image Credit & [3]Copyright: [4]Vikas Chander

   Explanation: South of the large star-forming region known as the Orion
   Nebula, lies bright blue reflection nebula [5]NGC 1999. At the edge of
   the [6]Orion molecular cloud complex some 1,500 light-years distant,
   NGC 1999's illumination is provided by the embedded variable star V380
   Orionis. The nebula is marked with a dark sideways T-shape at center
   right in [7]this telescopic vista that spans about two full moons on
   the sky. Its dark shape was once assumed to be an obscuring dust cloud
   seen in silhouette. But [8]infrared data suggest the shape is likely a
   hole blown through the nebula itself by energetic young stars. In fact,
   [9]this region abounds with energetic young stars producing jets and
   outflows with luminous shock waves. Cataloged as Herbig-Haro (HH)
   objects, named for astronomers George Herbig and Guillermo Haro, the
   shocks have intense reddish hues. HH1 and HH2 are just below and right
   of NGC 1999. HH222, also known as the [10]Waterfall nebula, looks like
   a red gash near top right in the frame. To create the shocks
   [11]stellar jets push through the surrounding material at speeds of
   hundreds of kilometers per second.

                 Tomorrow's picture: the western eastern sea
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    Authors & editors: [23]Robert Nemiroff ([24]MTU) & [25]Jerry Bonnell
                                 ([26]UMCP)
          NASA Official: Phillip Newman [27]Specific rights apply.
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                A service of: [29]ASD at [30]NASA / [31]GSFC
                           & [32]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2201/NGC-1999.jpg
   3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
   4. https://www.vikaschander.com/
   5. https://hubblesite.org/contents/media/images/2000/10/952-Image.html
   6. http://www.messier.seds.org/more/oricloud.html
   7. https://www.astrobin.com/68p5nt/
   8. https://arxiv.org/abs/1005.2202
   9. https://apod.nasa.gov/apod/ap180307.html
  10. https://hubblesite.org/contents/media/images/2000/10/952-Image.html
  11. https://apod.nasa.gov/apod/ap220121.html
  12. https://apod.nasa.gov/apod/ap220126.html
  13. https://apod.nasa.gov/apod/archivepix.html
  14. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  15. https://apod.nasa.gov/apod/lib/aptree.html
  16. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  17. https://apod.nasa.gov/apod/calendar/allyears.html
  18. https://apod.nasa.gov/apod.rss
  19. https://apod.nasa.gov/apod/lib/edlinks.html
  20. https://apod.nasa.gov/apod/lib/about_apod.html
  21. http://asterisk.apod.com/discuss_apod.php?date=220127
  22. https://apod.nasa.gov/apod/ap220128.html
  23. http://www.phy.mtu.edu/faculty/Nemiroff.html
  24. http://www.phy.mtu.edu/
  25. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  26. http://www.astro.umd.edu/
  27. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  28. https://www.nasa.gov/about/highlights/HP_Privacy.html
  29. https://astrophysics.gsfc.nasa.gov/
  30. https://www.nasa.gov/
  31. https://www.nasa.gov/centers/goddard/
  32. http://www.mtu.edu/