Astronomy Picture of the Day

                         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.

                                2019 April 17
                                      [2]
                                  Messier 81
  Image Credit & Copyright [3] : Paolo De Salvatore [4]  (Zenit Observatory)

Explanation: One of the brightest galaxies in planet Earth's sky is similar in
size to our Milky Way Galaxy: big, beautiful Messier 81 [5] . Also known as
NGC 3031 or Bode's galaxy for its 18th century discoverer, this grand spiral
[6]  can be found toward the northern constellation of Ursa Major, the Great
Bear. The detailed telescopic [7]  view reveals M81's bright yellow nucleus,
blue spiral arms, pink starforming regions, and sweeping cosmic dust lanes [8]
. Some dust lanes actually run through the galactic disk (left of center),
contrary to other prominent spiral [9]  features though. The errant dust lanes
[10]  may be the lingering result of a close encounter [11]  between M81 and
its smaller companion galaxy, M82 [12] . Scrutiny of variable stars in M81 has
yielded one of the best determined distances [13]  for an external galaxy --
11.8 million light-years.

                      Tomorrow's picture: pixels in space

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    Authors & editors: Robert Nemiroff [25] (MTU [26] ) & Jerry Bonnell [27]
                                  (UMCP [28] )
          NASA Official:  Phillip Newman Specific rights apply [29] .
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              A service of: ASD [31]  at NASA [32]  / GSFC [33]
                           & Michigan Tech. U. [34]
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Site notes:
  [1] archivepix.html
  [2] image/1904/M81salvatore.jpg
  [3] lib/about_apod.html#srapply
  [4] https://www.flickr.com/photos/paolodesalvator...
  [5] https://www.universetoday.com/47054/messier-8...
  [6] https://www.nasa.gov/feature/goddard/2017/mes...
  [7] https://www.flickr.com/photos/paolodesalvator...
  [8] http://www.spitzer.caltech.edu/images/
1070-ssc2003-06c-Spiral-Galaxy-Messier-81
  [9] http://burro.astr.cwru.edu/Academics/Astr222/... spiral.html
  [10] ap010112.html
  [11] ap130925.html
  [12] ap120326.html
  [13] http://adsabs.harvard.edu/abs/1994ApJ...427.....
  [14] ap190416.html
  [15] archivepix.html
  [16] lib/apsubmit2015.html
  [17] lib/aptree.html
  [18] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apo...
  [19] calendar/allyears.html
  [20] /apod.rss
  [21] lib/edlinks.html
  [22] lib/about_apod.html
  [23] http://asterisk.apod.com/discuss_apod.php?dat...
  [24] ap190418.html
  [25] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [26] http://www.phy.mtu.edu/
  [27] https://antwrp.gsfc.nasa.gov/htmltest/jbonnel...
  [28] http://www.astro.umd.edu/
  [29] lib/about_apod.html#srapply
  [30] https://www.nasa.gov/about/highlights/HP_Priv...
  [31] https://astrophysics.gsfc.nasa.gov/
  [32] https://www.nasa.gov/
  [33] https://www.nasa.gov/centers/goddard/
  [34] http://www.mtu.edu/

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