China's Chang'e 4 lander on the far side of the Moon has found a 'cavity' in the cosmic ray flux between Earth and Moon, indicating that galactic cosmic rays (GCRs) may not be as evenly distributed as previously thought. This discovery could potentially lead to effective strategies to reduce radiation exposure for astronauts and high-altitude pilots. The discovery was made by an international team of researchers who monitored the GCR flux from 31 lunar cycles and found a region where the proton flux was about 20 percent lower than it is in the rest of the orbit. This could potentially help mitigate the radiation hazard these charged particles pose. The researchers believe this may be due to the alignment of the interplanetary magnetic field, part of the Sun's magnetic field that stretches into the Solar System.