observation of the element technetium (the lightest chemical element without stable isotopes) in stars, by galactic gamma-ray line emitters (such as 26Al, 60Fe, and 44Ti), by radioactive-decay gamma-ray lines from the 56Ni decay chain observed from two supernovae (SN1987A and SN2014J) coincident with optical supernova light, and by observation of neutrinos from the Sun and from supernova 1987a. These observations have far-reaching implications. 26Al has a lifetime of a million years, which is very short on a galactic timescale, proving that nucleosynthesis is an ongoing process within our Milky Way Galaxy in the current epoch. Current descriptions of the cosmic evolution of elemental abundances are broadly consistent with those observed in the Solar System and galaxy, whose distribution spans twelve orders of magnitude (one trillion). The roles of specific cosmic objects in producing these elemental abundances are clear for some elements, and heavily debated for others. For example, iron is believed to originate mostly from thermonuclear supernova explosions (also called supernovae of type Ia), and carbon and oxygen is believed to originate mostly from massive stars and their explosions. Li, Be, and B are believed to originate from spallation reactions of cosmic-ray nuclei such as carbon and heavier nuclei, breaking these apart. Unclear is, in which sources nuclei much heavier than iron are produced; for the slow and rapid neutron capture reactions, different sites are discussed, such as envelopes of stars of either lower or higher masses, or supernova explosions versus collisions of compact stars. The transport of nuclear reaction products from their sources through the interstellar and intergalactic medium also is unclear, and there is, e.g., a missing metals problem of more production of heavy elements predicted than is observed in stars. Also, many nuclei that are involved in cosmic nuclear reactions are unstable and only predicted to exist temporarily in cosmic sites; we cannot easily measure the properties of such nuclei, and uncertainties on their binding energies are substantial. Similarly, stellar structure and its dynamics is not satisfactorily described in models and hard to observe except through asteroseismology; also, supernova explosion models lack a consistent description based on physical processes, and include heuristic elements. Future work Although the foundations of nuclear astrophysics appear clear and plausible, many puzzles remain. One example from nuclear reaction physics is helium fusion (specifically the 12C(α,γ)16O reaction(s)), others are the astrophysical site of the r-process, anomalous lithium abundances in Population III stars, and