  Our peculiar velocity with respect to the CMB rest frame is known to induce a
large dipole in the CMB. However, the motion of an observer has also the effect
of distorting the anisotropies at all scales, as shown by Challinor and Van
Leeuwen (2002), due to aberration and Doppler effects. We propose to measure
independently our local motion by using off-diagonal two-point correlation
functions for high multipoles. We study the observability of the signal for
temperature and polarization anisotropies. We point out that Planck can measure
the velocity $\beta$ with an error of about 30% and the direction with an error
of about 20 degrees. This method constitutes a cross-check, which can be useful
to verify that our CMB dipole is due mainly to our velocity or to disentangle
the velocity from other possible intrinsic sources. Although in this paper we
focus on our peculiar velocity, a similar effect would result also from other
intrinsic vectorial distortion of the CMB which would induce a dipolar lensing.
Measuring the off-diagonal correlation terms is therefore a test for a
preferred direction on the CMB sky.
