Cosmic rays come from the sun, as well as other sources, but mostly from the sun. Cosmic rays are highly charged particles, not a particular type or class of radiation, and are energetic enough to produce ionizing cascades in the atmosphere.
> Cosmic rays are highly charged particles, not a particular type or class of radiation
Highly charged particles are a type of radiation, at least as that term is used in the context of this discussion. (Yes, in some physics contexts "radiation" only refers to massless particles like photons, but in such a context no "radiation" to speak of comes from nuclear reactors either, since the potentially hazardous radiation from nuclear reactors is neutrons and some alphas and betas.)
https://en.wikipedia.org/wiki/Cosmic_ray