  Dust grains have been detected in various astronomical objects.
Interpretation of observations of dusty objects includes three components: 1)
determination of the materials which can exist in the solid phase and the
measurements or acquisition of their optical constants; 2) selection of the
light scattering theory in order to convert the optical constants into the
optical properties of particles; and 3) the proper choice of the object model
which includes, in particular, the correct treatment of the radiative transfer
effects. The current state of the components of dust modeling and the
reliability of information obtained on the cosmic dust from transmitted,
scattered and emitted radiation are discussed.
