Radionuclides with half-lives ranging from some years to billions of years
presumably synthesized outside of the solar system are now recorded in ``live''
or ``fossil'' form in various types of materials, like meteorites or the
galactic cosmic rays. They bring specific astrophysical messages the
deciphering of which is briefly reviewed here, with special emphasis on the
contribution of Dave Schramm and his collaborators to this exciting field of
research. Short-lived radionuclides are also present in the Universe today, as
directly testified by the gamma-ray lines emitted by the de-excitation of their
daughter products. A short review of recent developments in this field is also
presented.Comment: Invited Review to appear in New Astronomy, 16 pages, 2 figure
