The presence of relic neutrinos in the Universe is well established in any cosmological model. However, their detection has appeared always to be too difficult if not impossible. For these reasons the relic neutrino detection has generated a lot of very bizarre ideas ending with not feasible measurement. Subsequently the speaker, together with two other colleagues, published a paper (JCAP06, 2007, 015) in which the interaction of relic neutrino, with energy of milli eV, was discussed in details and the amazing results showing that neutrinos have a sizeable interaction cross section with a certain tipe of target nuclei was obtained for the first time. In the talk the most relevant outcomes of the paper and the conceptual design of a possible detector will be presented. In the second part of the talk the PTOLEMY project, dedicated to prove the feasibility of a possible relic neutrino detector, will be presented
