The Chandra X-Ray Observatory released this image on November 23, 2015, of a group of galaxies nicknamed the Cheshire Cat. Some of the features of the “cat” are distant galaxies whose light has been stretched and bent by gravitational lensing, an indication of large amounts of mass between us and these distant galaxy, and, Chandra says, most of that mass exists in the form of dark matter. “…the mass that distorts the faraway galactic light is found surrounding the two giant ‘eye’ galaxies and a ‘nose’ galaxy. The multiple arcs of the circular ‘face’ arise from gravitational lensing of four different background galaxies well behind the ‘eye’ galaxies.”
The “cat” will disappear in around a billion years.