  We test the usual hypothesis that the Cosmic Microwave Background (CMB)
dipole, its largest anisotropy, is due to our peculiar velocity with respect to
the Hubble flow by measuring independently the Doppler and aberration effects
on the CMB using Planck 2018 data. We remove the spurious contributions from
the conversion of intensity into temperature and arrive at measurements which
are independent from the CMB dipole itself for both temperature and
polarization maps and both SMICA and NILC component-separation methods.
Combining these new measurements with the dipole one we get the first
constraints on the intrinsic CMB dipole. Assuming a standard dipolar lensing
contribution we can put an upper limit on the intrinsic amplitude: 3.7 mK (95%
CI). We estimate the peculiar velocity of the solar system without assuming a
negligible intrinsic dipole contribution: $v = (300^{+111}_{-93})$ km/s with
$(l,b) = (276 \pm 33, 51 \pm 19)^\circ$ [SMICA], and $v = (296^{+111}_{-88})$
km/s with $(l,b) = (280 \pm 33, 50 \pm 20)^\circ$ [NILC] with negligible
systematic contributions. These values are consistent with the peculiar
velocity hypothesis of the dipole.
