Auroral Belts as Magnetically Localized Reactors for Prebiotic Chemistry on Early Earth

Most models of prebiotic chemistry emphasize globally distributed or widely acting energy sources, including ultraviolet radiation, lightning, impacts, and energetic particles. However, spatially localized environments capable of repeatedly concentrating reactive chemistry may also have contributed to sustaining nonequilibrium chemical evolution on the early Earth. Here, we propose that Earth's auroral belts may have acted as recurrent and spatially focused environments in which prebiotic reactions repeatedly occurred. Magnetically guided charged particles preferentially enter the atmosphere at high latitudes, depositing energy locally rather than uniformly across the planetary surface. Previous irradiation studies have shown that energetic particles are capable of driving the formation of amino acids, carboxylic acids, and hydrolysable organic precursors under plausible prebiotic conditions. Building upon these previous studies, we explore whether geomagnetic focusing could have spatially organized such particle-driven chemistry into recurrent high-latitude reaction environments. We therefore consider the possible chemical consequences of auroral particle precipitation in an early atmosphere dominated by N₂, CO₂, and H₂O, together with minor reduced gases. In contrast to broadly distributed energy inputs, auroral activity could have repeatedly supplied reactive compounds to restricted polar environments, where subsequent deposition and freeze–thaw concentration may have promoted further chemical evolution. The hypothesis yields several falsifiable predictions that distinguish magnetically localized particle-driven chemistry from ultraviolet- or lightning-dominated scenarios. If valid, planetary magnetic fields may have played an active role in spatially organizing chemical evolution on the early Earth and may also influence chemically favorable environments on other magnetized worlds.