This is an image of the <a href="https://en.wikipedia.org/wiki/dwarf_planet" class="extiw" title="en:dwarf planet">dwarf planet</a> <a href="https://en.wikipedia.org/wiki/Eris" class="extiw" title="en:Eris">Eris</a> (center) and its satellite <a href="https://en.wikipedia.org/wiki/Dysnomia" class="extiw" title="en:Dysnomia">Dysnomia</a> (at 9 o'clock position) taken with NASA's <a href="https://en.wikipedia.org/wiki/Hubble_Space_Telescope" class="extiw" title="en:Hubble Space Telescope">Hubble Space Telescope</a> on August 30, 2006. Hubble observations were obtained on Dec. 3, 2005 and Aug. 30, 2006 using the <a href="https://en.wikipedia.org/wiki/Advanced_Camera_for_Surveys" class="extiw" title="en:Advanced Camera for Surveys">Advanced Camera for Surveys</a>. The Hubble images were combined with images from the <a href="https://en.wikipedia.org/wiki/Keck_telescopes" class="extiw" title="en:Keck telescopes">Keck telescopes</a> taken on August 20, 21, 30, and 31 to measure the satellite's orbit and calculate a mass for Eris, which is the largest dwarf planet in the solar system.
NASA, ESA, and M. Brown (California Institute of Technology)
2006-08-30
<a rel="nofollow" class="external free" href="http://hubblesite.org/newscenter/archive/releases/2007/24/image/b/">http://hubblesite.org/newscenter/archive/releases/2007/24/image/b/</a> (<a rel="nofollow" class="external text" href="http://imgsrc.hubblesite.org/hu/db/images/hs-2007-24-b-full_jpg.jpg">direct link</a>)