              APOD: 2018 May 18 - Attack of the Laser Guide Stars

                         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 May 18
                                      [2]
                       Attack of the Laser Guide Stars
 Image Credit & License [3] : European Southern Observatory / Gerhard Hudepohl
                            (atacamaphoto.com [4] )

Explanation: Dodging powerful laser beams [5] , a drone captured this stunning
aerial view. The confrontation took place above the 8.2 meter diameter Very
Large Telescopes of the Paranal Observatory on planet Earth [6] . Firing
during a test of the observatory's 4 Laser Guide Star Facility, the lasers are
ultimately battling against the blurring effect of atmospheric turbulence by
creating artificial guide stars. The guide stars are actually emission from
laser excited sodium atoms at high altitudes within the telescopic field of
view [7] . Guide star image fluctuations are used in real-time to correct for
atmospheric blurring by controlling a deformable mirror in the telescope's
optical path. Known as adaptive optics [8] , the technique can produce images
at the diffraction limit [9]  of the telescope. That's the same sharpness you
would get if the telescope were in space [10] .

                    Tomorrow's picture: light-weekend [11]

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    Authors & editors: Robert Nemiroff [23] (MTU [24] ) & Jerry Bonnell [25]
                                  (UMCP [26] )
          NASA Official:  Phillip Newman Specific rights apply [27] .
              NASA Web Privacy Policy and Important Notices [28]
              A service of: ASD [29]  at NASA [30]  / GSFC [31]
                           & Michigan Tech. U. [32]
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Site notes:
  [1] archivepix.html
  [2] image/1805/DJI_0058.jpg
  [3] http://www.eso.org/public/outreach/copyright/
  [4] https://www.atacamaphoto.com/
  [5] http://www.eso.org/public/usa/images/potw1820a/
  [6] ap120421.html
  [7] ap170329.html
  [8] https://www.youtube.com/watch?v=gDGvNyVApgg
  [9] ap150507.html
  [10] http://spacetelescopelive.org/
  [11] ap180519.html
  [12] ap180517.html
  [13] archivepix.html
  [14] lib/apsubmit2015.html
  [15] lib/aptree.html
  [16] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  [17] calendar/allyears.html
  [18] /apod.rss
  [19] lib/edlinks.html
  [20] lib/about_apod.html
  [21] http://asterisk.apod.com/discuss_apod.php?date=180518
  [22] ap180519.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] 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/
