The hidden sides of the nucleus

This document presents in a very pedagogical way, the questions that have arisen through the most recent discoveries concerning the structure of nuclei. This document is made up of 7 brief articles, each one dedicated to a particular topic: 1) a thoroughly knowledge of exotic nuclei is necessary to the understanding of matter and the universe, 2) the historical aspect of the representation of the nucleus from its discovery in 1911 to the notion of halo introduced in the eighties, 3) the stability valley is challenged by the discovery of super-heavy nuclei more stable than expected, 4) the way of producing exotic nuclei is presented, 5) the decay through the emission of 2 protons has been observed for the first time with Fe45, 6) the shapes of nuclei are various and can be different between the fundamental state and an excited one for the same nucleus, and 7) halos and clusters inside nuclei. (A.C.)