For fifty years, Mercury's faint magnetic field — just one percent as strong as Earth's — posed a quiet riddle: could something so weak still shape the chaos of the solar wind? A new study published in Nature Astronomy, drawing on NASA's MESSENGER data and computer modeling, answers yes, but conditionally — the field periodically traps solar wind particles into fleeting radiation belts, existing half the time at Mercury's farthest orbital point and fading within hours. In resolving a debate that spanned two spacecraft missions, scientists have found in Mercury not merely a solved puzzle, but a