Cosmic rays are accelerated toward Earth by the same kind of supernova explosions that carved this bubble into the Large Magellanic Cloud. (Credit: Gemini South Telescope in Chile; composite by Travis Rector of the University of Alaska Anchorage)
Sometime in the last few million years, a not-so-far-off supernova sent charged particles known as cosmic rays out in all directions. The scattered, stripped nuclei of radioactive iron isotopes eventually made their way to Earth as part of a larger stream of material. Now, researchers at Washington University in St. Louis have found traces of this stream bombarding our planet, bringing interstellar atomic debris crashing into Earth.
In a paper published Thursday in Science, the researchers report on the findings of 17 years worth of observation from the Cosmic Ray Isotope Spectrometer aboard NASA’s ACE craft. During that time, it detected 15 individual nuclei of iron-60, a by-product of supernova explosions. Because ...
