                  APOD: 2017 July 27 - A Sagittarius Triplet

                         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.

                                 2017 July 27
                                      [2]
                            A Sagittarius Triplet
                Image Credit & Copyright [3] : Josep Drudis [4]

Explanation: These three bright nebulae are often featured on telescopic tours
of the constellation Sagittarius [5]  and the crowded starfields of the
central Milky Way [6] . In fact, 18th century cosmic tourist Charles Messier
[7]  cataloged two of them; M8 [8] , the large nebula above and left of
center, and colorful M20 [9]  near the bottom of the frame. The third emission
region includes NGC 6559 [10] , right of M8 and separated from the larger
nebula by a dark dust lane. All three are stellar nurseries about five
thousand light-years or so distant. Over a hundred light-years across the
expansive M8 is also known as the Lagoon Nebula. M20's popular moniker is the
Trifid. Glowing hydrogen gas creates the dominant red color of the emission
nebulae. In striking contrast, blue hues in the Trifid are due to dust
reflected starlight(link). The colorful composite skyscape [12]  was recorded
with two different telescopes to capture a widefield image of the area and
individual close-ups at higher resolution.

                   Tomorrow's picture: noodling around [13]

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  [2] image/1707/TOA1-M8M20-SL-DCP01andB600-09-Final7-Cc2048.jpg
  [3] lib/about_apod.html#srapply
  [4] http://www.astrodrudis.com/
  [5] http://www.hawastsoc.org/deepsky/sgr/ index.html
  [6] ap161110.html
  [7] http://messier.seds.org/xtra/history/biograph.html
  [8] ap160909.html
  [9] ap170628.html
  [10] ap040629.html
  [11] ap011228.html
  [12] https://astrodrudis.com/messier-8-messier-20-and-ic-4685/
  [13] ap170728.html
  [14] ap170726.html
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