We are living in an exciting time, where next-generation instruments and improved methods are leading to discoveries in astronomy, astrophysics, planetary science, and cosmology. As we look farther and in greater detail into the cosmos, some of the most enduring mysteries are finally being answered. Of particular interest are cosmic rays, the tiny particles consisting of protons, atomic nuclei, or stray electrons that have been accelerated to near the speed of light. These particles represent a major hazard for astronauts venturing beyond Earth’s protective magnetic field.
At the same time, cosmic rays regularly interact with our atmosphere (producing “showers” of secondary particles) and may have even played a role in the evolution of life on Earth. Due to the way they carry an electric charge, which scrambles their path as they travel through the Milky Way’s magnetic field, astronomers have been hard-pressed to find where cosmic rays originate. But thanks to a new study that examined 12 years of data from NASA’s Fermi Gamma-ray Space Telescope, scientists have confirmed that the most powerful originate from shock waves caused by supernova remnants.
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