Figure 6.8: In this drawing, the proper motion measured by an observer at the far left is the angle traversed per unit time, P m . However, the angle that is traversed on the sky is the same for a nea...Figure 6.8: In this drawing, the proper motion measured by an observer at the far left is the angle traversed per unit time, P m . However, the angle that is traversed on the sky is the same for a nearby star with a small tangential velocity, v small , and for a more distant star with a larger tangential velocity, v large . The distance to an object is given by d.
