  The inverse Compton scattering of interstellar photons off cosmic-ray
electrons seems to play a more important role in the generation of diffuse
emission from the Galaxy than thought before. The background radiation field of
the Galaxy is highly anisotropic since it is dominated by the radiation from
the Galactic plane. An observer in the Galactic plane thus sees mostly head-on
scatterings even if the distribution of the cosmic-ray electrons is isotropic.
This is especially evident when considering inverse Compton scattering by
electrons in the halo, i.e. the diffuse emission at high Galactic latitudes.
  We derive formulas for this process and show that the anisotropy of the
interstellar radiation field has a significant effect on the intensity and
angular distribution of the Galactic diffuse gamma rays, which can increase the
high-latitude Galactic gamma-ray flux up to 40%. This effect should be taken
into account when calculating the Galactic emission for extragalactic
background estimates.
