  A dual optical set-up is proposed to detect simultaneously the different
behavior of light from stellar and local sources, in relation to speed-induced
aberration. A small laser is set at the center of the objective lens of a
telescope, allowing to record at once the two spots on an array detector. Their
positions are recorded during a yearly earth orbit, so stellar aberration can
be visualized as a tiny circle. But no aberration has been observed from local
sources, hence the laser spot should remain still. The simultaneous recording
of both spots allows highlighting their different behavior. Einstein related
aberration to the transverse speed between light source and observer, and since
for local sources it is null, no aberration ensues. Despite this explanation
conforms with the correct result for local sources, it cannot however be
retained since stellar aberration does not vary although relative speed differs
for each star. Consequently, the null transverse velocity cannot be considered
the cause of the null aberration from local sources. A causal approach to this
different behavior between stellar and local light is advanced, based on the
combined effects of a speed-induced deflection of emitted light rays and a
speed-induced aberration upon detection.
