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.

                              2020 September 3
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                            A Halo for Andromeda
     Digital Illustration Credit: [3]NASA, [4]ESA, J. DePasquale and E.
                      Wheatley ([5]STScI) and Z. Levay

   Explanation: M31, the Andromeda Galaxy, is the closest large spiral
   galaxy to our Milky Way. Some 2.5 million light-years distant it shines
   in Earth's night sky as a small, faint, elongated cloud just visible to
   the unaided eye. Invisible to the eye though, its enormous halo of hot
   ionized gas is represented in purplish hues for [6]this digital
   illustration of our neighboring galaxy [7]above rocky terrain. Mapped
   by Hubble Space Telescope observations of the absorption of ultraviolet
   light against distant quasars, the extent and make-up of Andromeda's
   gaseous halo has been [8]recently determined by the AMIGA project. A
   reservoir of material for future star formation, Andromeda's halo of
   diffuse [9]plasma was measured to extend around 1.3 million light-years
   or more from the galaxy. That's about half way to the Milky Way, likely
   putting it in contact with the diffuse gaseous halo of our own galaxy.

                     Tomorrow's picture: pixels in space
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    Authors & editors: [21]Robert Nemiroff ([22]MTU) & [23]Jerry Bonnell
                                 ([24]UMCP)
          NASA Official: Phillip Newman [25]Specific rights apply.
              [26]NASA Web Privacy Policy and Important Notices
                A service of: [27]ASD at [28]NASA / [29]GSFC
                           & [30]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2009/STScI-H-p2046b-m-1999x2000.jpg
   3. https://www.nasa.gov/
   4. https://www.spacetelescope.org/
   5. https://www.stsci.edu/
   6. https://hubblesite.org/contents/media/images/2020/46/4735-Image
   7. https://apod.nasa.gov/apod/ap200326.html
   8. https://hubblesite.org/contents/news-releases/2020/news-2020-46
   9. https://arxiv.org/abs/2002.07818
  10. https://apod.nasa.gov/apod/ap200902.html
  11. https://apod.nasa.gov/apod/archivepix.html
  12. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  13. https://apod.nasa.gov/apod/lib/aptree.html
  14. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  15. https://apod.nasa.gov/apod/calendar/allyears.html
  16. https://apod.nasa.gov/apod.rss
  17. https://apod.nasa.gov/apod/lib/edlinks.html
  18. https://apod.nasa.gov/apod/lib/about_apod.html
  19. http://asterisk.apod.com/discuss_apod.php?date=200903
  20. https://apod.nasa.gov/apod/ap200904.html
  21. http://www.phy.mtu.edu/faculty/Nemiroff.html
  22. http://www.phy.mtu.edu/
  23. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  24. http://www.astro.umd.edu/
  25. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  26. https://www.nasa.gov/about/highlights/HP_Privacy.html
  27. https://astrophysics.gsfc.nasa.gov/
  28. https://www.nasa.gov/
  29. https://www.nasa.gov/centers/goddard/
  30. http://www.mtu.edu/