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 February 11
                                      [2]
                  New Data: Ultima Thule Surprisingly Flat
           Illustration Credit: NASA [3] , JHU's APL [4] , SwRI [5]

Explanation: Ultima Thule is not the object humanity thought that it was last
month. When the robotic New Horizons spacecraft [6]  zoomed past the distant
asteroid Ultima Thule (officially 2014 MU69 [7] ) in early January, early
images [8]  showed two circular lobes [9] that when most simply extrapolated
to 3D were thought to be, roughly, spheres. However, analyses of newly
beamed-back images -- including many taken soon after closest approach [10]
-- shows eclipsed stars re-appearing sooner than expected [11] . The only
explanation possible is that this 30-km long Kuiper belt object [12] has a
different 3D shape than believed only a few weeks ago. Specifically, as shown
in the featured illustration [13] , it now appears that the larger lobe --
Ultima -- is more similar to a fluffy pancake [14]  than a sphere, while the
smaller lobe -- Thule -- resembles a dented walnut [15] . The remaining
uncertainty in the outlines are shown by the dashed blue lines. The new shape
information indicates that gravity -- which (link)contracts more massive
bodies into spheres -- played perhaps less of a role in contouring the lobes
of Ultima Thule [16]  than previously thought. The New Horizons spacecraft
[17]  continued on to Ultima Thule after passing Pluto [18]  in mid-2015. New
data and images [19]  are still being received.

                         Tomorrow's picture: moon jet

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    Authors & editors: Robert Nemiroff [31] (MTU [32] ) & Jerry Bonnell [33]
                                  (UMCP [34] )
          NASA Official:  Phillip Newman Specific rights apply [35] .
              NASA Web Privacy Policy and Important Notices [36]
              A service of: ASD [37]  at NASA [38]  / GSFC [39]
                           & Michigan Tech. U. [40]
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Site notes:
  [1] archivepix.html
  [2] image/1902/MU69Flatter_NewHorizons_1920.jpg
  [3] https://www.nasa.gov/
  [4] https://www.jhuapl.edu/
  [5] https://www.swri.org/
  [6] https://www.nasa.gov/mission_pages/newhorizon...
  [7] https://en.wikipedia.org/wiki/(486958)_2014_M...
  [8] ap190103.html
  [9] ap190129.html
  [10] http://pluto.jhuapl.edu/News-Center/News-Arti...
  [11] https://i.imgflip.com/eyvnj.jpg
  [12] https://en.wikipedia.org/wiki/Kuiper_belt
  [13]
http://pluto.jhuapl.edu/Galleries/Featured-Im...
image.php?gallery_id=2&image_id=590
  [14] https://en.wikipedia.org/wiki/Pancake
  [15]
https://commons.wikimedia.org/wiki/File:Jugla...
  [16]
https://www.sciencealert.com/
we-ve-never-seen-something-like-this-orbiting-the-sun-ultima-thule-is-still-
weird
  [17] http://pluto.jhuapl.edu/Mission/Spacecraft.ph...
  [18] ap150831.html
  [19] http://pluto.jhuapl.edu/News-Center/News-Arti...
  [20] ap190210.html
  [21] archivepix.html
  [22] lib/apsubmit2015.html
  [23] lib/aptree.html
  [24] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apo...
  [25] calendar/allyears.html
  [26] /apod.rss
  [27] lib/edlinks.html
  [28] lib/about_apod.html
  [29] http://asterisk.apod.com/discuss_apod.php?dat...
  [30] ap190212.html
  [31] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [32] http://www.phy.mtu.edu/
  [33] https://antwrp.gsfc.nasa.gov/htmltest/jbonnel...
  [34] http://www.astro.umd.edu/
  [35] lib/about_apod.html#srapply
  [36] https://www.nasa.gov/about/highlights/HP_Priv...
  [37] https://astrophysics.gsfc.nasa.gov/
  [38] https://www.nasa.gov/
  [39] https://www.nasa.gov/centers/goddard/
  [40] http://www.mtu.edu/

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