  We predict a new mechanism for the spin light of neutrino ($SL\nu$) that can
be emitted by a neutrino moving in gravitational fields. This effect is studied
on the basis of the quasiclassical equation for the neutrino spin evolution in
a gravitational field. It is shown that the gravitational field of a rotating
object, in the weak-field limit, can be considered as an axial vector external
field which induces the neutrino spin procession. The corresponding probability
of the neutrino spin oscillations in the gravitational field has been derived
for the first time. The considered in this paper $SL\nu$ can be produced in the
neutrino spin-flip transitions in gravitational fields. It is shown that the
total power of this radiation is proportional to the neutrino gamma factor to
the fourth power, and the emitted photon energy, for the case of an ultra
relativistic neutrino, could span up to gamma-rays. We investigate the $SL\nu$
caused by both gravitational and electromagnetic fields, also accounting for
effects of arbitrary moving and polarized matter, in various astrophysical
environments. In particular, we discuss the $SL\nu$ emitted by a neutrino
moving in the vicinity of a rotating neutron star, black hole surrounded by
dense matter, as well as by a neutrino propagating in the relativistic jet from
a quasar.
