Stars have been caught crawling around the outskirts of the Milky Way more sluggishly than expected, a slow motion that scientists say can only be explained if our dark matter galaxy map is wrong.
Specific Velocities of stars around the edges of galaxies have historically been dead giveaways for the presence of dark matter in those galaxies. This is because astronomers can measure a galaxy's "rotation curve," which charts the orbital velocities of stars against their distances from the center of a galaxy.
