By closely mapping the mass of an enormous galactic collision, astronomers may have uncovered a type of force that only affects dark matter.

The results come from observations of the Musket Ball Cluster, a vast celestial object located about 5.23 billion light-years away in the constellation Cancer. Galaxies are usually gravitationally bound to other galaxies, creating massive galactic clusters. The Musket Ball Cluster is an example of what happens when two such galactic clusters -- each composed of hundreds of individual galaxies -- crash into one another.

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