Short answers, pulled from the story.
Paul Villard discovered gamma radiation in 1900 while studying radium. Ernest Rutherford officially named the phenomenon gamma rays in 1903 after recognizing its distinct properties from alpha and beta rays.
Gamma rays originate primarily through radioactive decay of isotopes like potassium-40 and cosmic ray interactions with atmospheric molecules. Lightning strikes generate terrestrial gamma-ray flashes that reach energies up to 100 MeV and are detected daily by space observatories such as the Fermi Gamma-ray Space Telescope.
The photoelectric effect dominates below 50 keV where photons transfer all energy to electrons, while Compton scattering prevails between 100 keV and 10 MeV. Pair production becomes possible above 1.02 MeV and dominates over 5 MeV in lead, converting photon energy into electron-positron pairs.
Solar flares emit across the entire electromagnetic spectrum including gamma rays with the first confident observation recorded in 1972. These events release intense radiation detectable near the visible universe edge within 10 billion light years.
Ernest Rutherford identified gamma rays as fundamentally different because they carry no charge and remain undeflected by magnetic fields unlike charged particles. This lack of charge allows them to penetrate deeper through matter compared to less penetrating alpha and intermediate beta rays.