... A rare galaxy type, polar ring galaxies have a substantial population of stars, gas, and dust orbiting in rings nearly perpendicular to the plane of the galactic disk. ... The polar ring component can be used to explore the shape of the galaxy's otherwise unseen dark matter halo by calculating the dark matter's gravitational influence on the rotation of the ring and disk. ... Publications with keywords: polar ring - galaxies - dark matter . ... Galaxy Cluster Abell 1689 Magnifies the Dark Universe ....