 Proxima Centauri, the nearest star outside the Solar System, is about four light-years away.In this frame of reference, in which Proxima Centauri is perceived to be moving in a circular trajectory with a radius of four light years, it could be described as having a speed many times greater than "c" as the rim speed of an object moving in a circle is a product of the radius and angular speed.It is also possible on a geostatic view, for objects such as comets to vary their speed from subluminal to superluminal and vice versa simply because the distance from the Earth varies.