The reality of this missing mass remained in question for decades, until the 1970s when American astronomers Vera Rubin and W. Originally known as the “missing mass,” dark matter’s existence was first inferred by Swiss American astronomer Fritz Zwicky, who in 1933 discovered that the mass of all the stars in the Coma cluster of galaxies provided only about 1 percent of the mass needed to keep the galaxies from escaping the cluster’s gravitational pull. Dark matter makes up 30.1 percent of the matter-energy composition of the universe the rest is dark energy (69.4 percent) and “ordinary” visible matter (0.5 percent).

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What is dark matter made of