Weekly Science Update

galaxy clusters
Dark matter and normal matter have been wrenched apart by the tremendous collision of two large clusters of galaxies. The galaxies are observed in the optical (shown in orange and white). Most of the normal mass in the clusters (pink) is associated with gas heated in their collision. Dark matter is not visible, but is inferred (blue) from gravitational lensing effects; the dark matter lagged behind the other matter in the collision. The discovery in 2008, using NASA's Chandra X-ray Observatory and other telescopes, provides additional evidence for the existence of dark matter.
Credit: NASA and the Chandra X-ray Observatory
Low Resolution Image (jpg)
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