Are you one of the authors of this paper? Email us from your institutional or work email address mentioning this article's arXiv ID and we'll verify you and give you edit access to this page.
By harnessing data from the IceCube Neutrino Observatory, scientists have, for the first time, mapped Earth’s density distribution, mass, and moment of inertia—using the dimming of high-energy neutrinos traversing the planet.
Abstract
Using 10.7 years of data from the IceCube Neutrino Observatory, scientists have reconstructed Earth's density profile. High-energy neutrinos (500 GeV – 100 TeV) are absorbed by matter depending on the traversed thickness and energy. By measuring the attenuation of the particle flux at different angles, a layered model of the interior was fitted, and the mass and polar moment of inertia were computed. These are the most accurate values obtained through the weak interaction; they agree with seismic and gravitational data. If seismology "listens" to the Earth, then neutrinos let us "see" its silhouette backlit.
Links in the knowledge graph 1
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. Just as astronomers study the atmospheres of distant worlds by how starlight filters through during a transit, the IceCube Neutrino Observatory at the South Pole has turned Earth into its own exoplanet. High-energy neutrinos born in active galactic nuclei and the vicinity of black holes illuminate the planet from within—and as this flux dims, the hidden structure of the core, mantle, and crust emerges.
To detect a single neutrino, you'd need a wall of lead a light-year thick. Yet Earth can attenuate a flux of 100 TeV neutrinos by nearly 50% if they travel through the core.
The IceCube telescope observes Cherenkov light—blue flashes occurring in the ice when charged muons zip through faster than light in that medium. Out of 368,071 tracks over 10.7 years, neutrinos with energies from 500 GeV to 100 TeV were selected. The key trick lies in the energy dependence of the cross-section: it grows as a power law, described by formulas from the Standard Model. So neutrinos of different energies ‘see’ different depths—yielding a kind of spectroscopy of Earth’s layers. The researchers modeled Earth as a set of concentric shells of constant density and used Bayesian analysis to reconstruct the radial density profile.
The result is not just a curve, but a portrait of the planet painted by the weak interaction. The profile matches the reference seismic model PREM to within tens of percent. For the first time, it separately yielded Earth’s mass (7.25×10^24 kg) and polar moment of inertia (1.05×10^38 kg·m²)—and both values fall within the confidence intervals of classical measurements. This means that the neutrino–nucleon cross-section, calibrated at accelerators, holds at planetary scales—fundamental physics and geology have played a duet.
At 1 TeV, a neutrino ‘feels’ only a few percent of Earth’s mass along its path, but at 100 TeV, it senses almost the entire bulk. It’s as if the planet gradually becomes opaque to ghost particles.
Neutrino tomography isn’t just an elegant cross-check of geophysical models. It paves the way toward planetary studies independent of seismometers and orbital gravimeters. In the future, with increased statistics from IceCube-Gen2 and the Mediterranean KM3NeT, we could peer into the heart of Mars to unravel why its magnetic dynamo fell silent, or probe the cores of gas giants. For now, the method demands ever more precise knowledge of astrophysical neutrino fluxes from supernovae, neutron stars, and pulsars, as well as refinements of nuclear effects in cross-sections—data from Antarctica keep pouring in, and each year brings new transparency.
🎯 To catch a single neutrino, you’d need a lead wall a light-year thick; yet Earth can weaken a beam of 100 TeV neutrinos by nearly half if they travel through the core.
