Galaxy rotation curve

Observed discrepancy in galactic angular momenta

The rotation curve of a disc galaxy (also called a velocity curve) is a plot of the orbital speeds of visible stars or gas in that galaxy versus their radial distance from that galaxy's centre. It is typically rendered graphically as a plot, and the data observed from each side of a spiral galaxy are generally asymmetric, so that data from each side are averaged to create the curve. The experimental curves observed are at significant variance with gravitational theory applied to the matter observed in a galaxy.

From Wikipedia, under CC BY-SA. More on occurri.