December 5, 2023
On this day, the universe repeated one of its rarest tricks: it arranged dust, light, memory, and possibility into a person no equation...
Energetic Particle Strikes the Earth
Birthday · December 5, 2023
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APOD published December 5, 2023. Full image credits are on the original APOD entry below. A publication-date match, not a photo taken on your date. Independent of NASA.
It was one of the most energetic particles ever known to strike the Earth -- but where did it come from? Dubbed Amaterasu after the Shinto sun goddess, this particle, as do all cosmic rays that strike the Earth's atmosphere, caused an air shower of electrons, protons, and other elementary particles to spray down onto the Earth below. In the featured illustration, a cosmic ray air shower is pictured striking the Telescope Array in Utah, USA, which recorded the Amaterasu event in 2021 May. Cosmic ray air showers are common enough that you likely have been in a particle spray yourself, although you likely wouldn't have noticed. The origin of this energetic particle, likely the nucleus of an atom, remains a mystery in two ways. First, it is not known how any single particle or atomic nucleus can practically acquire so much energy, and second, attempts to trace the particle back to where it originated did not indicate any likely potential source. Open Science: Browse 3,200+ codes in the Astrophysics Source Code Library