A rotation curve is a plot of the rotational velocity of a galaxy as a function of the distance away from the galactic center.Predictions for rotation curves for spiral galaxies suggest that the curve should decline beyond the galactic bulge.Actual measurements,however,show that the rotation curve is flat beyond the bulge.What does this deviation from prediction tell us about spiral galaxies,including the Milky Way?

Question

Quizplus · Accepted Answer

The deviation from the predicted decline in rotation curve beyond the bulge suggests the presence of a large amount of unseen mass surrounding the visible galaxy, known as dark matter. This is consistent with other observational evidence for the existence of dark matter in spiral galaxies as well as on larger scales.

A Rotation Curve Is a Plot of the Rotational Velocity