TOKYO -- Even when there are warning signs, predicting the exact timing of a volcanic eruption is impossible, as much about the inner workings of volcanoes remains a mystery. But that could change now that volcanologists have the geological equivalent of a doctor's X-ray at their disposal.
When cosmic radiation from supernova explosions and other events in deep space reaches Earth and collides with the atmosphere, large numbers of elementary particles called muons are generated. These so-called secondary cosmic rays account for 70% of the cosmic rays that reach the surface of the Earth. Hold out your hand, and one will pass through every second.