  We possess convincing experimental evidence for the fact that the real photon
has non-trivial parton structure. On the other hand, interactions of the cosmic
microwave background photons with high energy particles propagating through the
Universe play an important role in astrophysics. In this context, to invoke the
parton content could be convenient for calculations of the probabilities of
different processes involving these photons. As an example, the cross section
of inclusive resonant $W^+$ boson production in the reaction $\nu \gamma\to
W^+X$ is calculated by using the parton language. Neutrino--photon deep
inelastic scattering is considered.
