A. Novikov

Earth is a closed book for those accustomed to leafing through pages with light. But to neutrinos, the invisible particles born in cosmic rays and barely remembering the prediction of Pauli, our planet is a braille script: each kilometer of depth presses its relief into their…

For almost a century, seismology has been the planet’s chief X-ray, probing the interior through elastic waves. But neutrinos, ghost particles predicted by Wolfgang Pauli, offer a different perspective.

Deep beneath the ice of the South Pole, nearly two and a half kilometers down, an unusual telescope is at work. It is not pointed at the sky but through the Earth. Its quarry: neutrinos, nearly elusive particles that pass through planets and stars without interacting with anything.

Cosmic rays aren't rays in the usual sense: they're fast particles bombarding Earth from all directions. Mostly they're protons and atomic nuclei. Their energies vary widely, from modest to fantastically huge. When such a particle heads our way and the Moon or Sun gets in its path, it gets absorbed.