Muon Particles Rain From Space
High-energy cosmic rays collide with Earth's upper atmosphere and create showers of short-lived muons that reach sea level at nearly the speed of light. Detectors on the ground record thousands of these particles passing through every square meter each minute.
💡 Fun detail:
Because muons penetrate rock and metal easily, scientists use them to image the interiors of pyramids and volcanoes without drilling.
Source: NASA