Spectropolarimetry of solar prominences

The magnetic field is the most important physical parameter that drives the formation, the structuring and the eruption of solar prominences. Consequently, magnetic field measurements within prominences are fundamental for understanding the physics of these fascinating objects. Surprisingly however, very few of such measurements have been performed since old systematic observations made from the 70s up to the mid 80s! Even though these measurements brought landmark results, a lot still remains to be done concerning the temporal and spatial variations of the prominence magnetic field and its relationship with the fine structures of the plasma (e.g. feet/barbs and vertical threads). In this context, we discuss some properties of various empirical and MHD models that could be tested observationally in the near future with (very) large aperture telescopes and coronographs, associated with modern visible and IR spectropolarimetric instrumentation.