The Periodic Table is deceptively simple. However, its apparentsimplicity harbors a dark secret: we do not yet understand how all theelements it contains in its rank and file were first formed. Now, aEuropean-led team has examined models of a supernova's earliest momentsto try and fill our periodic knowledge gap. Carla Fröhlich of theUniversity of Basel, Switzerland, and colleagues have found that protonsin the proton-rich region surrounding a freshly formed neutron star,which lasts just seconds, can transform into neutrons by reacting withantineutrinos streaming from the neutron star. These extra neutrons arecritical during this period when the material is still hot enough tomake heavy, proton-rich isotopes, as nuclei packed with their fill ofprotons can grab these new neutrons. In so doing, they generate enoughbinding force to capture yet another proton shifting up the periodictable as they go. The work could explain the origins of isotopes of themetals molybdenum and ruthenium, which are proton heavy and contained inthe sun and meteorites, but have no clear origin in accepted nuclearreactions.