Fig12_14 Abell 2218

Fig12_14 Abell 2218

Fig. 12.14 . A Hubble Space Telescope image of a rich cluster of galaxies designated Abell 2218. It is about three billion light-years away from Earth. A typical rich cluster contains hundreds and even thousands of galaxies, each composed of hundreds of billions of stars and possibly up to ten times more mass within invisible dark matter. The galaxy cluster Abell 2218 is so massive and so compact that its gravity bends and focuses the light from galaxies that lie behind it. Multiple images of these background galaxies are distorted into long faint arcs. Magnified or ring images of individual background galaxies can also be observed. [Courtesy of NASA/STScI/Andrew Fruchter/the ERO team (Sylvia Baggett/STScI, Richard Hook/ST-ECF/Zoltan Levay, STScI).]

Copyright 2010, Professor Kenneth R. Lang, Tufts University