I have been doing research in high-energy astrophysics and solar physics since 1965, working at the Naval Research Laboratory until 2005 and at the University of Maryland since then. This included development of an early balloon-borne 10-150 MeV imaging gamma-ray telescope that suggested presence of a narrow band of emission along the Galactic plane and the first evidence for pulsed emission from the Crab Nebula. This was followed by studies with the HEAO-1 X-ray spectrometer, one of which indicated that GX339-4 was a black-hole system. My astrophysics studies continued in the 1980s‚ with studies of cosmic gamma-ray bursts, one of which was observed above 100 MeV, extended Galactic emission of 26Al and of 511 keV annihilation radiation, and observation of the 56Fe gamma-ray spectrum from SN1987A. As a result of these studies, I received the 1992 Rossi Prize and became a Fellow of the American Physical Society (1997) and the American Astronomical Society (2020). From 1989-1991 I was a Senior Staff Scientist in the Astrophysics Division at NASA Headquarters. After that time my research has focused on observations of gamma-rays from the Sun, using data from several instruments. I have used nuclear-line emission to understand the chromospheric abundance of elements and the accelerated abundance of nuclei in solar flares. One of these studies revealed a striking change in width of the 511-keV annihilation line in solar flares, suggesting that the ambient temperature changed from about 500,000 K to normal chromospheric temperature in two minutes during a flare. With the launch of the Fermi telescope, I studied >100 MeV gamma-ray emission in solar eruptions, cataloging late phase emission, and showing its association with CME shocks and the acceleration of solar energetic particles that can threaten astronauts and space instrumentation. My most recent studies resulted in the discovery of new component of flare-accelerated MeV electrons that interact in the solar corona.