The effect of the solar radiation on the interplanetary dust particle
is derived. The most simple correct derivation is presented (in terms
of order v/c) and each step is explained in detail. Derivation takes i
nto account the general case of a spherical particle, not only perfect
ly absorbing one as in the case of Robertson's derivation (Robertson,
1937). Some new results on relativistic covariant formula are also pre
sented.