Hierarchy classification:

1. top of the aat hierarchies
2. Associated Concepts Facet
3. Associated Concepts (hierarchy name)
4. scientific concepts
5. physical sciences concepts
6. physics concepts
7. [energy and related concepts]
8. energy
9. radiation (energy)
10. electromagnetic radiation

Anotations

Scope note:

High-energy particles arriving from outer space that are mainly protons (often referred to as hydrogen nuclei), but also include nuclei of heavier elements. When they arrive at Earth, they collide with the nuclei of atoms in the upper atmosphere, creating more particles.