I was reading the wikipedia entry for Dark matter halo here: https://en.wikipedia.org/wiki/Dark_matter_halo And they have this graph for the Milky Way galaxy rotation curve: "Galaxy rotation curve for the Milky Way. Vertical axis is speed of rotation about the galactic center. Horizontal axis is distance from the galactic center. The sun is marked with a yellow ball. The observed curve of speed of rotation is blue. The predicted curve based upon stellar mass and gas in the Milky Way is red" What I don't understand is that I found several other graphs for the Milky way rotation curve that look like this: Why in the wikipedia graph (top chart) is the predicted curve based on visible matter (red line) so different from the "visible matter only" line in the bottom graph. In the top chart the Sun sits at the intersection of the predicted (visible matter) and observed (visible + dark matter) lines.. but on the bottom graph they don't intersect at the sun. What am I missing here? Thanks for any help with this!