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 December 7
   [2]The featured image shows spectrograms for the first 90 gravitational
   wave events ever detected. Please see the explanation for more detailed
                                information.

             Ninety Gravitational Wave Spectrograms and Counting
     Image Credit: [3]NSF, [4]LIGO, [5]VIRGO, [6]KAGRA, [7]Georgia Tech,
      [8]Vanderbilt U.; Graphic : [9]Sudarshan Ghonge & [10]Karan Jani

   Explanation: Every time two massive [11]black holes collide, a loud
   chirping sound is broadcast out into the universe in [12]gravitational
   waves. Humanity has only had the technology to hear [13]these unusual
   chirps for the past seven years, but since then we have heard about 90
   -- during the first three observing runs. [14]Featured above are the
   spectrograms -- plots of gravitational-wave frequency versus time -- of
   these 90 as detected by the giant detectors of [15]LIGO (in the
   [16]USA), [17]VIRGO (in [18]Europe), and [19]KAGRA (in [20]Japan). The
   more [21]energy received on [22]Earth from a collision, the
   [23]brighter it appears on the graphic. Among many [24]science firsts,
   these [25]gravitational-radiation chirps are giving humanity an
   unprecedented [26]inventory of black holes and neutron stars, and a new
   way to [27]measure the expansion rate of our universe. A [28]fourth
   gravitational wave observing run with increased sensitivity is
   currently planned to begin in 2022 December.

                       Tomorrow's picture: comet tails
     __________________________________________________________________

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     __________________________________________________________________

    Authors & editors: [40]Robert Nemiroff ([41]MTU) & [42]Jerry Bonnell
                                 ([43]UMCP)
          NASA Official: Phillip Newman [44]Specific rights apply.
              [45]NASA Web Privacy Policy and Important Notices
                A service of: [46]ASD at [47]NASA / [48]GSFC
                           & [49]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2112/GWaveCatalog_LigoVirgo_5692.jpg
   3. https://www.nsf.gov/
   4. https://www.ligo.org/about.php
   5. http://public.virgo-gw.eu/the-virgo-collaboration/
   6. https://gwcenter.icrr.u-tokyo.ac.jp/en/organization
   7. https://physics.gatech.edu/
   8. https://as.vanderbilt.edu/physics/
   9. https://humansofligo.blogspot.com/2019/05/sudarshan-ghonge.html
  10. https://www.karanjani.com/
  11. https://apod.nasa.gov/apod/ap190414.html
  12. https://spaceplace.nasa.gov/gravitational-waves/en/
  13. https://www.ligo.caltech.edu/video/ligo20160211v2
  14. https://dcc.ligo.org/LIGO-G2102338/public
  15. https://youtu.be/PVNlPUcPlB0
  16. https://en.wikipedia.org/wiki/United_States
  17. http://public.virgo-gw.eu/virgo-in-a-nutshell/
  18. https://en.wikipedia.org/wiki/Europe
  19. https://gwcenter.icrr.u-tokyo.ac.jp/en/kagra-gallery
  20. https://en.wikipedia.org/wiki/Japan
  21. https://apod.nasa.gov/apod/ap171016.html
  22. https://www.nasa.gov/topics/earth/index.html
  23. https://i.pinimg.com/550x/81/21/c0/8121c0291fa14d1fe52b9eb007741cac.jpg
  24. https://arxiv.org/abs/2111.03606
  25. https://youtu.be/jtp71NT0GNg
  26. https://www.ligo.org/science/Publication-O3bAstroDist/
  27. https://www.ligo.org/science/Publication-O3Cosmology/
  28. https://www.ligo.org/scientists/GWEMalerts.php
  29. https://apod.nasa.gov/apod/ap211206.html
  30. https://apod.nasa.gov/apod/archivepix.html
  31. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  32. https://apod.nasa.gov/apod/lib/aptree.html
  33. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  34. https://apod.nasa.gov/apod/calendar/allyears.html
  35. https://apod.nasa.gov/apod.rss
  36. https://apod.nasa.gov/apod/lib/edlinks.html
  37. https://apod.nasa.gov/apod/lib/about_apod.html
  38. http://asterisk.apod.com/discuss_apod.php?date=211207
  39. https://apod.nasa.gov/apod/ap211208.html
  40. http://www.phy.mtu.edu/faculty/Nemiroff.html
  41. http://www.phy.mtu.edu/
  42. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  43. http://www.astro.umd.edu/
  44. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  45. https://www.nasa.gov/about/highlights/HP_Privacy.html
  46. https://astrophysics.gsfc.nasa.gov/
  47. https://www.nasa.gov/
  48. https://www.nasa.gov/centers/goddard/
  49. http://www.mtu.edu/