China’s Chang’e-6 reveals why solar wind hits the Moon’s two sides differently

China's Chang'e-6 mission returned far-side lunar soil samples that revealed the Moon's two hemispheres receive solar wind differently. Earth's magnetosphere slows solar wind from 400 km/s to about 200 km/s on the near side, while the far side gets hit by faster, more energetic particles that penetrate deeper into the soil. Noble gas isotopes preserved in the regolith now offer a way to study Earth's ancient magnetic history.