New Insights Reveal Layered Interiors of Uranus and Neptune: Explaining Their Unique Magnetic Fields

New research from UC Berkeley reveals insights into the interiors of Uranus and Neptune. This study suggests these ice giants have distinct layered structures composed of water and hydrocarbons.

Previous theories about Uranus and Neptune’s interiors have proposed ideas like diamond rain or super-ionic water. However, Burkhard Militzer’s recent findings, published in the Proceedings of the National Academy of Sciences, indicate that under extreme temperatures and pressures, water separates from hydrocarbons.

Militzer’s simulations show that beneath the dense atmospheres of these planets lies a water-rich layer. Below that, there is a denser layer filled with carbon, nitrogen, and hydrogen. This layered structure explains the planets’ unique magnetic fields, which do not resemble Earth’s dipolar magnetic field. Instead, Voyager 2 discovered that Uranus and Neptune have disorganized magnetic fields.

The study uses computer simulations of atoms that model the behavior of elements under conditions found inside these planets. At pressures over 3 million times that of Earth’s atmosphere, Militzer observed that hydrogen is squeezed out, which allows for the formation of two distinct layers. The lighter, water-rich layer is on top, while the denser, hydrocarbon-rich layer remains below.

The layered structure of these interiors also hinders convection, which is the process that typically creates magnetic fields. This explains why Uranus and Neptune exhibit such disordered fields. Militzer notes that this discovery could apply to similar ice giant planets in other star systems.

The predicted structure beneath Uranus includes a 5,000-mile-thick water-rich layer and a similarly thick hydrocarbon-rich layer. Neptune, despite being more massive, has comparable layers beneath its thinner atmosphere.

Future research aims to confirm these findings through laboratory experiments that simulate the extreme conditions of these planets. A proposed NASA mission to Uranus may provide further confirmation by measuring the planet’s vibrations, which could differ based on whether a planet has a layered structure or not.

This research enhances our understanding of the ice giants’ compositions and their magnetic fields and opens new avenues for exploration in planetary science.