Had enough mass to keep the rotation speed constant mention that I in the dark man this balls in stock orbiting me because my gravitat Dermallure ional board keeping in place but even if you couldn’t see me you would know there must be something here otherwise the star resume off in a straight line there must be something causing that gravity and that's how we know there must be dark matter move an estimated there was ten times more dark matter then ordinary illuminated stuff since then we've analyzed hundreds of galaxies and they all have the same pattern theAllroad pay too fast for their own good and .