Where do Galactic Cosmic Rays originate?

Outside the solar system from sources like supernova explosions

Galactic cosmic rays consist of high-energy particles that travel from beyond our solar system. These particles are typically accelerated by cataclysmic stellar events, such as supernovae, which propel matter at extreme speeds across the cosmos. Because they are omnipresent and highly penetrating, they constitute a chronic background radiation field that impacts any spacecraft leaving the vicinity of Earth, making them a major concern for long-duration missions to locations such as the Moon or Mars.