  Our proper acceleration with respect to the Cosmic Microwave Background
results in a real-time change of the angular position of distant extragalactic
sources. The cosmological component of this aberration drift signal, the
non-inertial motion generated by the large-scale distribution of matter, can in
principle be detected by future high-precision astrometric experiments. It will
provide interesting consistency tests of the standard model of cosmology, set
independent constraints on the amplitude of the Hubble constant and the linear
growth rate of cosmic structures, and be instrumental in searching for evidence
of new physics beyond the standard model. We present the formalism of this
novel cosmological test, discuss the physics to which it is sensitive and show
simulated forecasts of the accuracy with which it can be implemented.
