I am having trouble understanding how stars orbit around a spiral galaxy. First off, my understanding of the Local Standard of Rest (LSR) is that it is a point which corresponds to the average velocity of all the stars in the defined local neighbourhood. This point moves around the centre of the galaxy in a closed circle. Stars move around the galaxy in closed elliptical orbits with respect to the LSR, but in circular open orbits with respect to the fixed frame of the galaxy itself. I am having trouble visualing why this is so. And why is the elliptical motion retrograde wrt the frame rotating with the galaxy?? Is the epicycle motion (the ellipse) an elipse in a complete rotation around the galaxy, or does this mean that stars rotate around the LSR in an ellipse while the LSR rotates around the galaxy? This is all very confusing to me. I hope I can sort all this out... thanks!!!