Unsung hero cold cases – the Slipher file

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