File talk:GalacticRotation2.svg

I was taught that rotational velocity is not a proper term. The proper term is angular velocity. In addition, with the made up term, there is no definition of units for it. It could be velocity in space (Meters per second) or radians per second). There is no supporting data in this file nor an obvious reference to the supporting data. I am forced to guess if the relationship noted is constant velocity (outer stars move through space at the same rate, thus distorting the arm of the galaxy with time (outer stars will not keep their angular position relative to inner stars) or if the arms hold their shape over time by all maintaining their angular velocity (or revolutions per millennium). — Preceding unsigned comment was added by 184.15.229.191 (talk) 12:53, 19 June 2017 (UTC)