I will start the talk by presenting neutrinos, the lightest and the weakest interacting fermions of the standard model. While they propagate the three flavor states go through a quantum coherent interference effect refereed to as neutrino oscillations.
Besides the fundamental physics implication the fact that neutrinos interact very weakly allows us to use them to explore regions that were inaccessible with other mediators such as photons. We can detect neutrinos coming from the interior of the Sun allowing us to see the product of the nuclear reactions, and in the last years we saw the first very high energy neutrinos from still unknown extra-galactic sources. In this talk we will look at the Earth interior with neutrinos for the first time by doing a tomography of the Earth via Weak interactions.