- This project calculates the value of β for ice particles based on wavelength dependent values of their refractive and absorptive indices. β is the ratio of the force due to radiation to the force due to gravity acting on a particle in the solar system. This parameter can later be used to determine the angle by which the trajectory of a particle changes upon entering the solar system. The radiation pressure is found using equations from the scattering theories of Mie and Debye. A computer program was used to create a table of values of the efficiency factor for radiation pressure, Qpr· Each value of Qpr in the table corresponds to value of λ. Each value of Qpr was multiplied by the value of the Planck function at that wavelength. The integral of this product function, which is proportional to β, was found using a list integration function in Mathematica. Using wavelength dependent values of the absorptive and refractive indices gives a Qpr function significantly different than those using constant values. This leads to the calculation of a realistic β value.