The CMB can be used as a test for the Global Isotropy of the Universe. Since the release of WMAP there have been several claims of a departure from Isotropy, as a power asymmetry between two opposite hemispheres at about 3 $\sigma$. After the release of the Planck data it has become possible to study such asymmetries also at very small angular scales. I will present a recent analysis of this issue on the Planck satellite maps taking into account carefully of three crucial ingredients: the presence of a mask, the anisotropy of the noise and the presence of Doppler and aberration effects due to our boosted reference frame. I will also review in general such effects of a boosted frame on the CMB, which induce measurable correlations between different multipoles that can be used as an independent measurement of our peculiar velocity and which can also induce biases in cosmological parameter estimation for small sky experiments.