Polarization of Light and Astronomical Observation

Light that is received from celestial bodies is polarized any time that an asymmetry occurs at the stage of emission or during the transfer of radiation towards the observer. Polarimetry therefore allows the acquisition of useful data that would be difficult to obtain using other methods in various astrophysical situations: surface and atmosphere of the Sun and the stars, detection of magnetic fields. For the first time, these different fields of study are presented from the same perspective, highlighting the common logic of all polarization phenomena. They are described in a mostly qualitative way, with as few mathematical formulas as possible, so both professional and amateur astronomers may benefit from this reading. Numerous references including the most recent works allow the reader to go deeper into the field.