What causes cosmic rays?
Protons mostly comprise high energy cosmic rays, those formerly mysterious beams that are accelerated to remarkable velocities. When they collide with the Earth’s atmosphere, they produce a blast of energy and other particles that can be detected on the surface. To give an idea how fast these particles are moving, just a single particle can have the same energy as fast moving tennis ball. In fact, if a high energy cosmic ray and a beam of light were to race across our galaxy (assuming one could race a beam of light!), the light beam would not win by much! However, our atmosphere protects us from the potential danger they pose in space. A team of 370 researchers from 17 countries have been working on the answer using the newly developed Pierre Auger Cosmic Ray Observatory, located in the mountains of South America. The observatory is essentially an array of detectors spread out over a 3,000 square kilometer area. As the cosmic rays collide with the atmosphere, the resulting spray of par
