More than a decade of data about the particles zipping around our sun could be used to solve many mysteries, from the behaviour of individual particles to the history of our solar system – while raising new questions
By Karmela Padavic-Callaghan
3 February 2025
The AMS particle detector on the International Space Station
NASA
An 11-year-long survey of the particles and antiparticles near our sun is unlocking our solar system’s history – and raising new mysteries about the particles themselves.
“It’s like when you walk into a dark room and see many, many new things,” says Samuel Ting at the Massachusetts Institute of Technology.
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We live in a cosmic void so empty that it breaks the laws of cosmology
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Space is filled with energetic particles, which travel in bursts called cosmic rays. When a cosmic ray enters the Alpha Magnetic Spectrometer (AMS) detector on the International Space Station (ISS), magnetic fields separate its particles based on their electric charge, and then the detector measures their masses and energies. This separation is crucial because it helps identify differences in the behaviour of a particle and its antiparticle, which is identical except with an opposite charge, says Ting.
He and his colleagues at the AMS Collaboration analysed more than 11 years of AMS data and found, surprisingly, that we don’t know as much about particle behaviour as we thought. For instance, the survey revealed trends in the number of particles over time, and in the ways different types of particles interacted with each other. There are more than 600 theoretical models that could possibly explain each of these trends – but none simultaneously explain both findings, says Ting.
And the survey’s results may matter for more than single particles. Researchers have been capturing cosmic rays with different detectors for more than a century because their changing properties could serve as records of the solar system’s history, says Jamie Rankin at Princeton University. But we never before had such a detailed understanding of how the solar cycle affects the rays, she says.