  Most astrophysical fluids are turbulent and magnetized. Fluctuations of
polarization provide a promising way to study astrophysical magnetic
turbulence. We discuss polarization that arises from grains and atoms aligned
in respect to magnetic field, describe the processes of alignment, explain when
the alignment reflects the direction of magnetic field. We show that temporal
fluctuations of interplanetary magnetic field can be studied using aligned
sodium atoms.
