Astronomy and astrophysics with neutrinos.

The article discusses the role of high-energy neutrinos as an astronomical messenger from extreme astrophysical environments in transversing cosmological distances without bending or energy loss. The neutrino energy spectrum at Earth's surface is shown. Diffusion in the galaxy's magnefic fields governed the trajectories of galactic cosmic rays. Neutrinos occupy an interesting comer of the standard mode as the lightest of the fermions and the most weakly interacting of all known particles.