  Exact solution of the modified Dirac equation in rotating medium is found in
polar coordinates in the limit of vanishing neutrino mass. The solution for the
active left-handed particle exhibit properties similar to those peculiar for
the charged particle moving in the presence of a constant magnetic field.
Accordingly, the particle in the rotating matter has circle orbits with energy
levels, analogous to the Landau levels in magnetic field. The relevant physical
realization of the problem is motion of neutrino inside the rotating neutron
star. The feature of such motion to form binding states leads to the prediction
of the new mechanism for neutrino trapping. The solution found can be used for
detailed description of relativistic and nearly massless neutrino dynamics in
neutron stars. Results obtained further develop the "method of exact solutions"
in application to particle interactions in presence of dense matter.
