  The Solar System harbors deep unresolved mysteries despite centuries-long
study. A highly intriguing case concerns anomalous non-dipolar and
non-axisymmetric magnetic fields of Uranus and Neptune that have long eluded
explanation by the prevailing theory. A thin-shell dynamo conjecture captures
observed phenomena but leaves unexplained fundamental material basis and
underlying mechanism. Here, we report the discovery of trihydrogen oxide (H3O)
in metallic liquid state stabilized at extreme pressure and temperature
conditions inside these icy planets. Calculated stability pressure field
compared to known pressure-radius relation for Uranus and Neptune places
metallic liquid H3O in a thin-shell zone near planetary cores. These findings
from accurate quantum mechanical calculations rationalize the empirically
conjectured thin-shell dynamo model and establish key physical benchmarks that
are essential to elucidating the enigmatic magnetic-field anomaly of Uranus and
Neptune, resolving a major mystery in planetary science.
