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.

                               2018 November 15
                                      [2]
                              Comet 46P/Wirtanen
    Image Credit & Copyright [3] : Alex Cherney (Terrastro [4] , TWAN [5] )

Explanation: Periodic Comet 46P/Wirtanen [6]  is now the brightest comet in
the night sky, but too faint to be seen by eye. From dark sky sites it could
just become naked-eye visible though, as it's 5.4 year long looping orbit
takes it closest to Earth [7]  and the Sun in mid December. Fluorescing in
sunlight [8] , its spherical coma is about half the angular size of a full
moon in this southern hemisphere telescopic view from November 7 [9] . Then
the comet was about 2 light-minutes away or 35 million kilometers from
Earth-bound telescopes, so the pretty greenish coma seen here is around
150,000 kilometers across. That makes it about the size of Jupiter. The stack
of digital images also reveals a very faint tail extending toward 4 o'clock
with a distant background galaxy notable at the upper left. As a regular
visitor to the inner Solar System, comet 46P/Wirtanen was once the favored
rendezvous target for ESA's comet exploring Rosetta mission [10] .

                          Tomorrow's picture: look up

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    Authors & editors: Robert Nemiroff [22] (MTU [23] ) & Jerry Bonnell [24]
                                  (UMCP [25] )
          NASA Official:  Phillip Newman Specific rights apply [26] .
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              A service of: ASD [28]  at NASA [29]  / GSFC [30]
                           & Michigan Tech. U. [31]
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Site notes:
  [1] archivepix.html
  [2] image/1811/46PCherney_NoText.jpg
  [3] lib/about_apod.html#srapply
  [4] http://www.terrastro.com/about/
  [5] http://www.twanight.org/cherney/
  [6] https://earthsky.org/space/ 46p-wirtanen-possibly-visible-to-eye-dec-2018
  [7] https://science.nasa.gov/news-articles/ close-approach-comets
  [8] ap130207.html
  [9] image/1811/46PCherney_small.jpg
  [10] http://sci.esa.int/rosetta/14615-comet-67p/
  [11] ap181114.html
  [12] archivepix.html
  [13] lib/apsubmit2015.html
  [14] lib/aptree.html
  [15] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apo...
  [16] calendar/allyears.html
  [17] /apod.rss
  [18] lib/edlinks.html
  [19] lib/about_apod.html
  [20] http://asterisk.apod.com/discuss_apod.php?dat...
  [21] ap181116.html
  [22] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [23] http://www.phy.mtu.edu/
  [24] https://antwrp.gsfc.nasa.gov/htmltest/jbonnel...
  [25] http://www.astro.umd.edu/
  [26] lib/about_apod.html#srapply
  [27] https://www.nasa.gov/about/highlights/HP_Priv...
  [28] https://astrophysics.gsfc.nasa.gov/
  [29] https://www.nasa.gov/
  [30] https://www.nasa.gov/centers/goddard/
  [31] http://www.mtu.edu/

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