                 APOD: 2018 June 19 - Ancients of Sea and Sky

                         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 June 19
                                      [2]
                           Ancients of Sea and Sky
                  Image Credit & Copyright: Jingyi Zhang [3]

Explanation: They may look like round rocks, but they're alive. Moreover, they
are modern versions of one of the oldest known forms of life: stromatolites
[4] . Fossils indicate that stromatolites [5]  appeared on Earth about 3.7
billion years ago -- even before many of the familiar stars [6]  in the modern
night sky were formed. In the featured image taken [7]  in Western Australia
[8] , only the ancient central arch of our Milky Way Galaxy [9]  formed
earlier. Even the Magellanic Clouds [10] , satellite galaxies of our Milky Way
and visible in the featured image below the Milky Way's arch [11] , didn't
exist in their current form when stromatolites [12]  first grew on Earth.
Stromatolites [13]  are accreting biofilms of billions of microorganisms [14]
that can slowly move toward light. Using this light to liberate oxygen [15]
into the air, ancient stromatolites helped make Earth [16]  hospitable to
other life forms [17]  including, eventually, humans [18] .

                Almost Hyperspace: Random APOD Generator [19]
                  Tomorrow's picture: pillars of stars [20]

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    Authors & editors: Robert Nemiroff [32] (MTU [33] ) & Jerry Bonnell [34]
                                  (UMCP [35] )
          NASA Official:  Phillip Newman Specific rights apply [36] .
              NASA Web Privacy Policy and Important Notices [37]
              A service of: ASD [38]  at NASA [39]  / GSFC [40]
                           & Michigan Tech. U. [41]
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Site notes:
  [1] archivepix.html
  [2] image/1806/MilkyWayStromatolites_Zhang_1587.jpg
  [3] mailto: jingyi .dot. tia .dot. zhang @at@ gmail .dot. com
  [4] https://en.wikipedia.org/wiki/Stromatolite
  [5]
http://seapics.com/feature-subject/marine-invertebrates/
stromatolite-pictures.html
  [6] https://www.quora.com/How-old-are-the-stars-we-see-from-the-sky
  [7] https://www.youtube.com/watch?v=d3-M9TxWtJg
  [8] https://en.wikipedia.org/wiki/Western_Australia
  [9] https://solarsystem.nasa.gov/resources/285/the-milky-way-galaxy/
  [10] https://en.wikipedia.org/wiki/Magellanic_Clouds
  [11] ap170821.html
  [12] https://www.youtube.com/watch?v=F6q-cD1j5RY
  [13] http://www.fossilmuseum.net/Tree_of_Life/Stromatolites.htm
  [14] https://www.biocote.com/blog/microorganisms-an-introduction/
  [15] https://en.wikipedia.org/wiki/Great_Oxygenation_Event
  [16] ap070325.html
  [17] https://i.imgur.com/pePvHU3.jpg
  [18] ap160815.html
  [19] https://apod.nasa.gov/apod/random_apod.html
  [20] ap180620.html
  [21] ap180618.html
  [22] archivepix.html
  [23] lib/apsubmit2015.html
  [24] lib/aptree.html
  [25] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  [26] calendar/allyears.html
  [27] /apod.rss
  [28] lib/edlinks.html
  [29] lib/about_apod.html
  [30] http://asterisk.apod.com/discuss_apod.php?date=180619
  [31] ap180620.html
  [32] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [33] http://www.phy.mtu.edu/
  [34] https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  [35] http://www.astro.umd.edu/
  [36] lib/about_apod.html#srapply
  [37] https://www.nasa.gov/about/highlights/HP_Privacy.html
  [38] https://astrophysics.gsfc.nasa.gov/
  [39] https://www.nasa.gov/
  [40] https://www.nasa.gov/centers/goddard/
  [41] http://www.mtu.edu/
