Neutrinos are not bent by magnetic fields and point back to their source. They can come from very dense and distant objects without being absorbed and bring new information about the most energetic astrophysical events. In combination with other cosmic particles (photons, gammas, cosmic rays and gravitational waves) they can elucidate the mechanisms of the most powerful cosmic accelerators.
The atmosphere is a copious source of neutrinos in a wide energy range. They can be used to test our knowledge of their interactions and properties. Indeed, atmospheric neutrinos were historically one of the origins of the discovery of neutrino oscillations. Atmospheric neutrinos allow us to look for non-standard interactions, sterile neutrinos, neutrino decay and other possible beyond the Standard Model processes.
The Universe is filled with this mysterious matter whose existence is inferred from its gravitational effects. To find out its nature and characteristics is one of the most pressing questions in modern physics. Some types of dark matter would accumulate at the centre of massive astrophysical objects, annihilate and produce high energy particle, especially neutrinos.