  Composition of Comet dust obtained by the dust impact analyser on the Halley
probes indicated that the comet dust is a mixure of silicate and carbonaceous
material. The collected interplanetary dust particles (IDP's) are fluffy and
composite having grains of several different types stuck together. Using
Discrete Dipole Approximation (DDA) we study the scattering properties of
composite grains. In particular, we study the angular distribution of the
scattered intensity and linear polarization of composite grains. We assume that
the composite grains are made up of host silicate sphere/spheroid with the
inclusions of graphite. Results of our calculations on the composite grains
show that the angle of maximum polarization shifts, and the degree of
polarizaion varies with the volume fraction of inclusions. We use these results
on the composite grains to interpret the observed scattering in the cometary
dust.
