A $100 detector can see invisible particles raining down from space

A pocket-sized, roughly $100 detector can reveal the invisible stream of cosmic particles constantly passing through Earth and even through our bodies. What began as a student physics project is now being used in major experiments, balloon missions, and potentially future spacecraft. A $100 detector can see invisible particles raining down from space.

The particles help scientists learn more about the universe’s most extreme phenomena. Many of these particles are linked to cosmic rays, extremely energetic particles that can come from exploding stars and other violent events far beyond our solar system. When cosmic rays strike atoms high in Earth’s atmosphere, they create showers of secondary particles.

Among them are muons, which can travel through the atmosphere and even penetrate underground. University of Delaware physics professor Spencer Axani has developed a device called CosmicWatch that makes it much easier to detect these otherwise invisible particles. The technology is now being used by everyone from high school students to professional researchers.