While looking at the <a href="https://en.wikipedia.org/wiki/galaxy_cluster" class="extiw" title="en:galaxy cluster">galaxy cluster</a> <a href="https://en.wikipedia.org/wiki/Abell_2667" class="extiw" title="en:Abell 2667">Abell 2667</a>, astronomers found an odd-looking <a href="https://en.wikipedia.org/wiki/spiral_galaxy" class="extiw" title="en:spiral galaxy">spiral galaxy</a> (shown here in the upper left hand corner of the image) that ploughs through the cluster after being accelerated to at least 3.5 million km/h by the enormous combined gravity of the cluster's <a href="https://en.wikipedia.org/wiki/dark_matter" class="extiw" title="en:dark matter">dark matter</a>, hot gas and hundreds of galaxies.
NASA, ESA, and J. Kneib (Laboratorie d'Astrophysique de Marseille)
<ul><li><a rel="nofollow" class="external free" href="http://hubblesite.org/newscenter/archive/releases/2007/12/image/a/">http://hubblesite.org/newscenter/archive/releases/2007/12/image/a/</a> (<a rel="nofollow" class="external text" href="http://imgsrc.hubblesite.org/hu/db/images/hs-2007-12-a-full_jpg.jpg">direct link</a>)</li>
<li><a rel="nofollow" class="external free" href="http://www.spacetelescope.org/images/heic0705a/">http://www.spacetelescope.org/images/heic0705a/</a></li></ul>