Countless cosmic particles constantly stream through Earth’s atmosphere and pass directly through our bodies without detection. Among these invisible visitors, neutrinos represent the most abundant type, with an estimated 100 trillion traversing each person every second. These ghostly particles originate primarily from the sun’s nuclear fusion reactions, though some originate from distant galaxies. Despite their astronomical numbers, neutrinos barely interact with ordinary matter, making them nearly impossible to notice or detect.
Beyond neutrinos, muons—subatomic particles created when cosmic rays collide with Earth’s atmosphere—also penetrate our bodies regularly. At ground level, approximately one to two muons pass through a human hand each second. Unlike neutrinos, muons can interact with matter due to their electrical charge. Additional cosmic particles, including neutrons, contribute to the radiation exposure humans receive, particularly at higher altitudes during air travel.
Scientists have developed sophisticated methods to study these cosmic visitors. The IceCube Neutrino Observatory in Antarctica uses thousands of light sensors surrounding a cubic kilometer of ice to detect the rare occasions when neutrinos collide with atomic nuclei. By recording these interactions and calculating detection efficiency, researchers can estimate the total neutrino flux passing through our planet and bodies.
The radiation from cosmic particles poses minimal health risk, with annual exposure comparable to a few chest X-rays. These energetic visitors have bombarded Earth throughout its history and continue to provide valuable scientific insights into the universe’s most violent phenomena, from supernovas to black holes, reminding us of our profound connection to the cosmos.
Originally reported by Livescience →
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