Information about the physical properties (i.e. shape, size distribution, porosity, albedo) of the interplanetary dust particles is essential, together with the knowledge of their chemical composition and of their dynamics, to infer their origin, and to allow some comparisons between the different dust populations, which replenish the interplanetary dust cloud. The determination of the physical properties from dust samples analysis is restricted to interplanetary dust particles collected in the near-Earth environment, while the estimation of the physical properties by dust impact studies is mainly performed on-board satellites and space probes. The physical (and chemical) properties of dust particles belonging to still inaccessible regions of the interplanetary dust cloud can thus only be approached through observations of the light scattered (or emitted) by these particles.
This review first summarises the light scattering properties of the interplanetary dust, with emphasis on local information retrieved by inversion techniques. These scattering properties are then compared with those of other (real or virtual) dust particles. Finally, the various laboratory tools that allow light scattering measurements by dust clouds to be interpreted are presented, and the constraints that may be derived about the physical properties of interplanetary and cometary dust are discussed.
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