To feel out the contours of the pyramid’s unexplored interior, scientists followed the paths of tiny subatomic particles called muons. Those particles, born high in Earth’s atmosphere, hurtled toward the surface and burrowed through the pyramid. Some of the particles imprinted hints of what they encountered on sensitive detectors in and around the pyramid. The particles’ paths revealed the surprising presence of the hidden chamber , announced in 2017 ( SN: 11/25/17, p. 6 ). That stunning discovery sparked plans among physicists to use muons to explore other archaeological structures. And some researchers are using the technique, called muography, to map out volcanoes’ plumbing. “You can see inside the volcano, really,” says geophysicist Giovanni Leone of Universidad de Atacama in Copiapó, Chile. That internal view could give scientists more information about how and when a volcano is likely to erupt Muons are everywhere on Earth’s surface. They’re produced when ...