                         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 May 20
                Planets of the Solar System: Tilts and Spins
     Video Credit: NASA [2] , Animation: James O'Donoghue [3] (JAXA [4] )

Explanation: How does your favorite planet spin? Does it spin rapidly around a
nearly vertical axis, or horizontally, or backwards? The featured video [5]
animates NASA [6]  images of all eight planets [7]  in our Solar System [8]
to show them spinning side-by-side [9] for an easy comparison. In the
time-lapse video [10] , a day on Earth -- one Earth rotation -- takes just a
few seconds. Jupiter [11]  rotates the fastest, while Venus [12]  spins not
only the slowest (can you see it?), but backwards. The inner rocky planets,
across the top, most certainly underwent dramatic spin-altering collisions
[13]  during the early days of the Solar System. The reasons why planets spin
and tilt [14]  as they do remains a topic of research [15] with much insight
gained from modern computer modeling [16]  and the recent discovery and
analysis of hundreds of exoplanets [17] : planets orbiting other stars [18] .

                Tomorrow's picture: sagittarian reds and blues

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    Authors & editors: Robert Nemiroff [30] (MTU [31] ) & Jerry Bonnell [32]
                                  (UMCP [33] )
          NASA Official:  Phillip Newman Specific rights apply [34] .
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              A service of: ASD [36]  at NASA [37]  / GSFC [38]
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Site notes:
  [1] archivepix.html
  [2] https://www.nasa.gov/
  [3] https://twitter.com/physicsJ
  [4] http://global.jaxa.jp/
  [5] https://www.youtube.com/watch?v=MS8KA7Mayho
  [6] https://www.nasa.gov/
  [7] ap060828.html
  [8] https://solarsystem.nasa.gov/solar-system/our-solar-system/in-depth/
  [9] https://www.youtube.com/watch?v=plpvWGOAL4o
  [10] https://www.youtube.com/embed/my1euFQHH-o
  [11] https://solarsystem.nasa.gov/planets/jupiter/overview/
  [12] https://solarsystem.nasa.gov/planets/venus/overview/
  [13] https://mobile.arc.nasa.gov/public/iexplore/missions/pages/yss/june.html
  [14]
https://geekologie.com/2019/01/a-simple-animation-of-the-tilt-and-rotat.php
  [15] http://allwallps.com/bin/02/54/72a.jpg
  [16] http://adsabs.harvard.edu/abs/2001Natur.411..767C
  [17] https://exoplanets.nasa.gov/
  [18] ap151205.html
  [19] ap190519.html
  [20] archivepix.html
  [21] lib/apsubmit2015.html
  [22] lib/aptree.html
  [23] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  [24] calendar/allyears.html
  [25] /apod.rss
  [26] lib/edlinks.html
  [27] lib/about_apod.html
  [28] http://asterisk.apod.com/discuss_apod.php?date=190520
  [29] ap190521.html
  [30] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [31] http://www.phy.mtu.edu/
  [32] https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  [33] http://www.astro.umd.edu/
  [34] lib/about_apod.html#srapply
  [35] https://www.nasa.gov/about/highlights/HP_Privacy.html
  [36] https://astrophysics.gsfc.nasa.gov/
  [37] https://www.nasa.gov/
  [38] https://www.nasa.gov/centers/goddard/
  [39] http://www.mtu.edu/
