AS102 Study Guide - Final Guide: Dennis Amiss
Document Summary
The actual rotation curve for the galaxy is the entire red curve out to the right-hand end of the graph. The flatness of the curve came as a shock because it implies that most of the mass of the galaxy must lie well beyond our. In fact, most must lie in the galactic halo. But relatively few stars have been observed in the halo. Because we cannot see this mass that must reside in the halo, the mass has been labelled as dark matter because it does not emit any light. Furthermore, the missing mass could be as much as 90% of the galaxy"s mass! Here is a link to a neat animation showing the rotation curve for the milky way galaxy. Use your cursor to move along the curve from close to the centre of the nucleus out to the furthest reaches of the galaxy.
