Here is a cosmic head-scratcher if there ever was one: Dark matter — an invisible, fundamental part of the universe — is supposed to be everywhere, with researchers "observing" its unobservable existence by following how the particles influence the movement of light or celestial bodies such as stars. Now scientists have found something that no one even knew was possible, The Associated Press writes: a galaxy with no dark matter at all.
Yale University astronomer Pieter van Dokkum stumbled upon the ancient galaxy, which is "as big as the Milky Way but with only 1 percent of its stars," AP writes. When he and his team went to measure the speed of star clusters in the galaxy, which should have been moving about 67,000 miles per hour, they found the clusters were moving a sluggish 18,000 miles per hour instead. That would only make sense if there was no dark matter at all acting on them — a finding confirmed when the researchers subsequently calculated the mass of the galaxy.
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