Radiative Grain Alignment

Polarization due to aligned dust grains was discovered in the interstellar medium more than 60 years ago. A quantitative, observationally well tested theory of the phenomenon has finally emerged in the last decade, promising not only an improved understanding of interstellar magnetic fields, but new tools for studying the dust environments and grain characteristics. This Radiative Alignment Torque (RAT) theory also has many potential applications in solar system physics, including for comet dust characteristics. I will review the main aspects of the theory and the observational tests performed to date, as well as some of the new possibilities for using polarization as a tool to study dust and its environment, with RAT alignment.