Source: How a super-energetic particle from outer space could help physics (The Hindu, January 11, 2024)
In May 2021, a powerful cosmic-ray event was found by Toshihiro Fujii, a Japanese scientist. He named it Amaterasu, after a sun goddess.
- Second-Highest-Energy Cosmic Ray: The ray Amaterasu was very strong. It was second in strength only to one other cosmic ray known. This finding was reported in Science.
- Telescope Array Project Data: Fujii works at Osaka Metropolitan University in Japan. He found Amaterasu in data from the Telescope Array Project in the U.S. This data was from 2008 to 2021.
- What Are Cosmic Rays?: They are fast particles and groups of particles from space and the sun. These include protons and alpha particles, which are helium nuclei. Most cosmic rays don’t reach the ground. They lose energy in the air and create other particles.
- Importance of Cosmic Rays: Studies on cosmic rays have been around since the 1930s. They helped find unknown particles. But where cosmic rays come from and why they are so energetic is still a mystery. This mystery has lasted for more than 86 years.
Understanding Cosmic Rays
- Solar Cosmic Rays: Solar cosmic rays mainly consist of protons. They usually come from solar flares. These are energetic events on the sun’s surface.
- The Composition of Cosmic Rays: Scientists measure cosmic rays for their composition. They found that for every 100 grams of protons, there are 28 grams of helium. This ratio matches early cosmic matter.
- Galactic Cosmic Rays: Galactic cosmic rays hit Earth often. They come from events beyond our solar system like supernova explosions. A supernova happens when a big star dies and erupts.
Cosmic Ray Composition
- Hydrogen and Heavier Elements: Approximately 89% of Galactic Cosmic Rays (GCRs) consist of hydrogen. The rest include all elements up to uranium.
- Ionization: These cosmic elements are fully ionized. This means they lack electrons and affect magnetic fields.
- The Sun’s Influence: The sun’s magnetic fields change the GCRs’ energy levels reaching Earth.
- Earth’s Atmospheric Impact: When GCRs hit Earth’s atmosphere, they ionize air molecules. This occurs at least 3 km above the surface.
- Energy: The energy of a recently discovered cosmic ray was extremely high. It helps refine our theories about cosmic phenomena.