Final answer:
Cosmic rays, high-energy particles such as protons and helium nuclei, travel to Earth at speeds up to 90% the speed of light, carrying energy comparable to starlight. Their source is difficult to pinpoint due to deflection by magnetic fields but supernova shocks are a significant contributor. They contribute to Earth's background radiation with more intense exposure towards the poles.
Step-by-step explanation:
The student has queried about the rate at which cosmic rays carry energy to the Earth. Cosmic rays are a form of high-energy radiation that predominantly consists of high-speed atomic nuclei and electrons. These rays can travel at speeds nearing 90% the speed of light. The primary components of cosmic rays are hydrogen nuclei, known as protons, which make up almost 90% of these rays, with helium and heavier nuclei constituting about 9%. Additionally, cosmic rays contain a small percentage of electrons and positrons. Positrons are positively charged particles with the same mass as electrons and are considered a form of antimatter.
The energy carried by cosmic rays to the Earth's atmosphere is approximately one-billionth of the energy we receive from the Sun. However, this energy is on par with what we receive in the form of starlight. The origin of cosmic rays is varied; while some originate from the Sun, the majority come from outside our solar system. Due to the deflection caused by magnetic fields, pinpointing their exact source is challenging.
Supernova shocks are thought to be a major source of cosmic ray production. Upon entering Earth's atmosphere, cosmic rays can cause extensive particle showers, releasing significant amounts of energy, sometimes approaching a joule, which translates to about 1010 giga electron volts (GeV). These showers can extend over multiple square kilometers, contributing to the background radiation on Earth, with higher doses near the poles compared to the equator.