Galaxy Cluster Abell 1689. Photo © NASA Goddard Photo and Video (August 19, 2010). Credit: NASA, ESA, E. Jullo (JPL/LAM), P. Natarajan (Yale) and J-P. Kneib (LAM).
NASA's Goddard Center is reporting a significant breakthrough in the study of Dark Matter. The purple halo you see in the centre of this image from late August is the distribution of Dark Matter in the cluster. More precisely, it is "impression of the gravitational field created by the dark matter."
NASA: "An international team of astronomers using gravitational lensing observations from the NASA/ESA Hubble Space Telescope has taken an important step forward in the quest to solve the riddle of dark energy, a phenomenon which mysteriously appears to power the Universe's accelerating expansion. Their results appear in the 20 August 2010 issue of the journal Science. This image shows the galaxy cluster Abell 1689, with the mass distribution of the dark matter in the gravitational lens overlaid (in purple). The mass in this lens is made up partly of normal (baryonic) matter and partly of dark matter. Distorted galaxies are clearly visible around the edges of the gravitational lens. The appearance of these distorted galaxies depends on the distribution of matter in the lens and on the relative geometry of the lens and the distant galaxies, as well as on the effect of dark energy on the geometry of the Universe." To view a video about this image go here.