Most models of prebiotic chemistry focus on globally distributed energy sources such as ultraviolet radiation, lightning, or impacts. However, spatially localized environments capable of repeatedly concentrating reactive chemistry may also have played an important role in sustaining nonequilibrium chemical evolution on the early Earth. Here, we propose that Earth’s polar auroral belts may have acted as persistent, spatially focused environments in which prebiotic reactions could repeatedly occur. Magnetically guided charged particles from the solar wind preferentially access the atmosphere through high-latitude cusp regions, depositing energy locally rather than uniformly across the planetary surface. This geomagnetic focusing may have generated geographically restricted reaction zones characterized by recurrent plasma–atmosphere interactions. We outline the physical basis of auroral particle precipitation and discuss its potential chemical consequences in a nitrogen- and carbon dioxide–rich prebiotic atmosphere. Order-of-magnitude estimates of auroral energy deposition and radiochemical production rates suggest that particle precipitation could provide a sustained source of reactive intermediates in localized regions. The hypothesis also yields several falsifiable predictions that distinguish particle-driven chemistry from UV- or lightning-dominated scenarios. If valid, this framework implies that planetary magnetic fields may have played an active role in shaping chemical evolution on early Earth and may influence the distribution of chemically favorable environments on magnetized exoplanets exposed to active stellar winds.
Shinya Kato (Thu,) studied this question.