Solar cosmic rays: 75 years of research

The 28th of February 2017 marked the 75th anniversary of the first confident detection of solar cosmic rays (SCRs), a term referring to accelerated solar particles with energies from about $10^6$ to $\sim 10^{10}\!-\!10^{11}\ $ eV. The present paper reviews the key observational and theoretical results on SCRs that have been accumulated over this period. The history of the discovery of SCRs is briefly described, together with SCR recording tech„niques and instruments, and some physical, methodical, and practical aspects of SCR generation are discussed in more detail. Special attention is given to mech„anisms of charged particle acceleration at and near the Sun. Current ideas on the interaction of solar cosmic rays with the solar atmosphere, peculiarities of their transport in interplanetary magnetic fields, movements in Earth's magnetosphere, and their impact on Earth's atmosphere are reviewed. It is shown that this field of space physics has produced many results of fundamental interest for astrophysics, solar–terrestrial physics, geophysics, and practical cosmonautics (astronautics).