One hundred years ago, an American astronomer by the name of Vesto Slipher became the first to measure streams of galaxies in our local neighborhood. Slipher used the 24-inch telescope at Lowell Observatory to measure galaxy velocities. Most of the galaxies he measured are receding from the Milky Way rather than moving toward it — the first indication of cosmic expansion. Read more in Dark Energy Detectives. Video: Dark Energy Survey
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