                         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 September 18
                            Salt, Pepper, and Ice
             Video Credit & Copyright: Maroun Habib (Moophz [2] )

Explanation: There's a "camera" comet now moving across the sky. Just a bit
too dim to see with the unaided eye, Comet 21P / Giacobini-Zinner [3]  has
developed a long tail [4] that makes it a good sight for binoculars and
sensitive cameras. The movement of the Comet 21P [5]  on the sky was captured
last week in the featured time-lapse video [6]  compressing 90 minutes into
about 2.5 seconds. What might seem odd is that the 21P's tail [7]  is not
following the comet's movement. This is because comet tails [8]  always point
away from the Sun, and the comet [9]  was not moving toward the Sun [10]
during the period photographed. Visible far in the background on the upper
left is the Salt & Pepper star cluster, M37 [11] , while the bright red star
V440 Auriga [12]  is visible just about the frame's center. This 2-km ball of
dust-shedding ice [13] passed its nearest to the Sun and Earth only last week
and is now fading as it crosses into southern skies [14] . Comet 21P should
remain visible, however, and photogenic to stabilized cameras [15] , for
another month or so.

                    Tomorrow's picture: a rose for a swan

-------------------------------------------------------------------------------
< [16] | Archive [17] | Submissions [18] | Index [19] | Search [20] | Calendar
  [21] | RSS [22] | Education [23] | About APOD [24] | Discuss [25] | > [26]
-------------------------------------------------------------------------------

    Authors & editors: Robert Nemiroff [27] (MTU [28] ) & Jerry Bonnell [29]
                                  (UMCP [30] )
          NASA Official:  Phillip Newman Specific rights apply [31] .
              NASA Web Privacy Policy and Important Notices [32]
              A service of: ASD [33]  at NASA [34]  / GSFC [35]
                           & Michigan Tech. U. [36]
----------
Site notes:
  [1] archivepix.html
  [2] https://moophz.com/photography
  [3] https://en.wikipedia.org/wiki/21P/Giacobini%E2%80%93Zinner
  [4] ap180913.html
  [5]
https://www.skyandtelescope.com/observing/
comet-21p-giacobini-zinner-shines-in-september/
  [6] https://www.youtube.com/watch?v=R60m1W7t1og
  [7] ap180823.html
  [8] https://spaceplace.nasa.gov/review/tails-of-wonder/
  [9] http://www.calsky.com/?Comets=&sec=3&step=1&number=21P
  [10] https://solarsystem.nasa.gov/solar-system/sun/by-the-numbers/
  [11] https://en.wikipedia.org/wiki/Messier_37
  [12] https://www.universeguide.com/star/v440aurigae
  [13]
https://www.csmonitor.com/Science/2015/0126/
What-is-comet-dust-made-of-Rosetta-finds-out
  [14] https://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=21P
  [15] ap120508.html
  [16] ap180917.html
  [17] archivepix.html
  [18] lib/apsubmit2015.html
  [19] lib/aptree.html
  [20] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  [21] calendar/allyears.html
  [22] /apod.rss
  [23] lib/edlinks.html
  [24] lib/about_apod.html
  [25] http://asterisk.apod.com/discuss_apod.php?date=180918
  [26] ap180919.html
  [27] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [28] http://www.phy.mtu.edu/
  [29] https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  [30] http://www.astro.umd.edu/
  [31] lib/about_apod.html#srapply
  [32] https://www.nasa.gov/about/highlights/HP_Privacy.html
  [33] https://astrophysics.gsfc.nasa.gov/
  [34] https://www.nasa.gov/
  [35] https://www.nasa.gov/centers/goddard/
  [36] http://www.mtu.edu/
