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.
"It's sort of non-negotiable," said van Dokkum of the baffling conclusion, which is being taken seriously by other scientists working in the field. "There's nothing else, just the stars."
Case Western Reserve astronomer Stacy McGaugh confirmed that the findings make no sense, but, well, there they are anyway. "Not sure what to make of it, but it is definitely intriguing," she said. "This is a weird galaxy."
Curiously, the lack of dark matter in the galaxy (which has the prosaic name "NGC1052-DF2") could actually help scientists better prove dark matter's existence. Learn how at The Associated Press, and read everything you need to know about dark matter here at The Week.