Cavity-enhanced graphene

Lunar swirls are delicate light-coloured markings on the Moon’s surface. The lighter soil is unweathered, having been somehow shielded from the solar wind. Although lunar swirls are known to be associated with anomalous magnetic fields, their exact origin has remained mysterious — however, Ruth Bamford and colleagues have now tied together satellite data, laboratory experiments and a theoretical model to better understand the formation of these swirling patterns. Bamford et al. suggest that the magneticfield component of the solar wind and the magnetic anomalies on the lunar surface create a ‘bubble’ bounded by a strong magnetic field. Solar-wind electrons are deflected by this barrier, but heavier ions pass through: this charge separation gives rise, in turn, to an electric field that further deflects charged particles. The result is an effective shield that protects large areas of the lunar surface from the impact of the solar wind. Interestingly, the deflection strength of the electric field depends on the magnetic field gradient of the bubble and not its actual size. Magnetic anomalies associated with lunar swirls cover areas of hundreds of kilometres, but the topology of the magnetic bubbles is irregular, creating alternating shielded and unshielded regions and forming complex light and dark patterns. IG