Importance of an astrophysical perspective in teaching relativity

The importance of a teaching a clear definition of the `observer' in special relativity is highlighted using a simple astrophysical example from the exciting current research area of `gamma-ray burst' astrophysics. The example shows that a source moving relativistically toward a single observer at rest exhibits a time `contraction' rather than a `dilation' because the light travel time between the source and observer decreases with time. Astrophysical applications of special relativity complement idealized examples with real applications and very effectively exemplify the role of a finite light travel time.