        APOD: 2018 May 30 - The Case of the Backwards Orbiting Asteroid

                         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 May 30
                 The Case of the Backwards Orbiting Asteroid
  Illustration Video Credit & Copyright: Western U. [2] , Athabasca U. [3] ,
                      Large Binocular Telescope Obs. [4]

Explanation: Why does asteroid 2015 BZ509 orbit the Sun the backwards? As
shown in the featured animation, Jupiter's trojan asteroids [5]  orbit the Sun
[6]  in two major groups -- one just ahead of Jupiter [7] , and one just
behind -- but all orbit the Sun [8]  in the same direction as Jupiter.
Asteroid BZ509 [9]  however, discovered in 2015 and currently unnamed, orbits
the Sun in retrograde and in a more complex gravitational dance with Jupiter
[10] . The reason why is currently unknown and a topic of research -- but if
resolved might tell us about the early Solar System [11] . A recently popular
hypothesis [12]  holds that BZ509 [13] was captured by Jupiter from
interstellar space [14]  billions of years ago, while a competing conjecture
posits that BZ509 came from our Solar System's own distant Oort cloud [15]  of
comets, perhaps more recently. The answer may only become known after more
detailed models of the likelihood and stability of orbits [16]  near Jupiter
are studied [17] , or, possibly, by observing direct properties of the unusual
object.

                      Tomorrow's picture: open space [18]

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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]
                           & Michigan Tech. U. [39]
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Site notes:
  [1] archivepix.html
  [2] http://www.physics.uwo.ca/
  [3] http://www.athabascau.ca/
  [4] http://www.lbto.org/
  [5] https://en.wikipedia.org/wiki/Trojan_(astronomy)
  [6] https://solarsystem.nasa.gov/solar-system/sun/overview/
  [7] https://solarsystem.nasa.gov/planets/jupiter/in-depth/
  [8] ap180204.html
  [9] https://en.wikipedia.org/wiki/(514107)_2015_BZ509
  [10] ap180226.html
  [11] https://solarsystem.nasa.gov/solar-system/our-solar-system/in-depth/
  [12] http://adsabs.harvard.edu/abs/2018arXiv180509013N
  [13] http://www.astro.uwo.ca/~wiegert/2015BZ509/
  [14] ap171122.html
  [15]
https://solarsystem.nasa.gov/bosf/docs/
01_09%20Capture%20and%20orbit%20of%20a%20comet%201280x720.png
  [16] https://en.wikipedia.org/wiki/Lagrangian_point
  [17]
https://d32xvgr96w2oxp.cloudfront.net/2013/06/
media-image-346120-article-ajust_930.jpg
  [18] ap180531.html
  [19] ap180529.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=180530
  [29] ap180531.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/
