Cosmic rays are high-energy particles that travel through space and reach Earth from various sources, including the Sun and distant supernovae. These particles are primarily protons, but they can also include heavier atomic nuclei and electrons. When cosmic rays collide with atoms in the Earth's atmosphere, they create secondary particles that can be detected by scientific instruments. These rays are important for understanding the universe, as they provide insights into cosmic events and the nature of dark matter. While most cosmic rays are harmless, they can pose a risk to astronauts and high-altitude flights due to increased radiation exposure.