  The paper presents a relativistic space-time diagram, which displays in true
values the space (Cartesian and polar) and the time coordinates of the same
event detected from two inertial reference frames in relative motion related by
the Lorentz-Einstein transformations, the aberration angles and the Doppler
shifted periods and wavelengths. We use it in order to illustrate the
reflection of light on moving mirrors (horizontal and vertical) and the way in
which a single observer could measure the length of a moving rod. It displays
in true values the space-time coordinates of the same event generated by a
light signal.
