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New Models Suggest Uranus and Neptune May Be Rock-Dominated, Not Ice Giants

Sparse measurements leave the rock-versus-ice picture unresolved despite new peer-reviewed models.

Overview

  • The University of Zurich team used a multi-step algorithm that merges empirical density profiles with equations of state to generate physically consistent interior models.
  • Two Neptune solutions exceed 50% rock by mass, and one Uranus solution reaches about 61% silicate, implying rock-rich worlds capped by thick ice layers.
  • The models place the magnetism-generating conducting layer relatively shallow—around 70% of Uranus’s radius and roughly 78–92% for Neptune—consistent with their tilted, multipolar fields.
  • Data remain too limited to discriminate rock-dominated from ice-dominated configurations, with Voyager 2 still the only spacecraft to have flown by either planet.
  • The research is published in Astronomy & Astrophysics, and the authors urge targeted missions and improved high-pressure material data to resolve the competing scenarios.