An analysis of material collected by China's Chang'e 6 mission now suggests that Earth's magnetosphere is responsible for much of this contrast. The findings were published in Nature Geoscience. Moon Dust Preserves a Solar Wind Record The solar wind is a constant flow of fast-moving charged particles released by the Sun. Because the Moon lacks a thick atmosphere and a global magnetic field, these particles strike its surface directly. Over time, the lunar regolith has stored evidence of this exposure. It acts as a natural archive of volatile materials delivered by the solar wind, including the noble gases (He, Ne, Ar, Kr, Xe). Because these elements rarely react chemically with other materials, scientists can use them as reliable markers of how solar wind particles entered and accumulated in lunar soil. Until recently, researchers could study samples only from the Moon's near side. Without material from the far side, they could not directly test whether solar wind implantation differed systematically between the two hemispheres. That changed when China's Chang'e 6 mission brought back 1.935 grams of regolith from the South Pole Aitken basin on the lunar far side. The samples provided the first direct opportunity to compare how solar wind particles...