Neutrino astrophysics and telescopes

The interest in detecting high energy neutrinos of astrophysical origin is motivated by the potentials of these weakly interacting particles. As a matter of fact, they would open a new window on the universe, complementing gamma-astronomy. Cherenkov detectors of huge dimensions are needed due to the small neutrino cross section and the low expected fluxes from sources. Moreover, these detectors need to be located in sea/lake depths or in the South Pole ice in order to be shielded by the huge amount of particles produced in atmospheric showers. Here we describe the neutrino telescope experimental technique, that is optimized for very high energies. The current status of running and under construction neutrino telescopes is summarized.