  We discuss the large scale polarization of the cosmic microwave background
induced by the anisotropy of the spatial geometry of our universe. Assuming an
eccentricity at decoupling of about $0.64 10^{-2}$, we find an average large
scale polarization $\Delta T_{pol}/ T_0 = (0.5 - 1.0) 10^{-6}$. We suggest that
the fortcoming polarization data at large scales from Planck will be able to
discriminate between our proposal and the generally accepted reionization
scenario.

Cosmology and Nongalactic Astrophysics;General Relativity and Quantum Cosmology;High Energy Physics - Phenomenology