Overview

• The spacecraft crossed the heliospheric current sheet and recorded in situ signatures of merging magnetic islands and reconnection exhausts.
• Trapped proton populations were energized up to roughly 400 keV, exceeding the available magnetic energy per particle by a factor of a thousand.
• Analysis differentiated these particles from solar flare emissions, confirming HCS reconnection as their unique acceleration site.
• Energy released during reconnection helps heat the solar corona and drives acceleration of the emerging solar wind.
• Findings offer pathways to refine space weather forecasts, inform laboratory fusion research and advance understanding of cosmic plasma processes.