The Virgo Cluster is so massive that it is noticeably pulling our Galaxy toward it. The cluster contains not only galaxies filled with stars but also gas so hot it glows in X-rays . Motions of galaxies in and around clusters indicate that they contain more dark matter than any visible matter we can see. False colors have been used to represent the intensity of X-ray emission. Because galaxy clusters are the largest structures in the Universe , this mysterious Dark Matter must dominate the cosmos but its nature is still an open question .
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