Wacky magnetic fields of ice giants may stem from conductivity changes in their deep interiors

A study published in Communications Physics suggests that the unusual magnetic fields of Uranus and Neptune may be caused by changes in electrical conductivity in their deep interiors. The research, led by Chi Yan from The University of Texas at Austin, models how fluid motion, temperature, and magnetic fields interact to generate the planets' dynamos. The findings indicate that the magnetic fields of these ice giants could change significantly over time, unlike Earth's stable dipole field. The study uses computer simulations to recreate the magnetic fields observed by NASA's Voyager 2 probe, which found that Uranus and Neptune's magnetic fields are highly disordered.

The researchers found that the magnetic fields of Uranus and Neptune are tilted by 59 degrees and 47 degrees respectively, unlike Earth's nearly upright dipole. They propose that the large size and unique geochemical composition of these ice giants could contribute to their unusual magnetic fields. The simulations suggest that the magnetic fields may change substantially within decades, potentially leading to different configurations than observed during the Voyager 2 mission. The study's lead author, Chi Yan, notes that Earth's magnetic tilt drifts by only a degree or so over 50 years, but the ice giants could behave very differently, with some stretches showing a tens-of-degrees shift within decades.

The researchers are analyzing high-resolution images from the James Webb Space Telescope to study the auroras of Uranus and Neptune, which could provide clues about the evolution of their magnetic fields. They plan to combine data from the JWST auroral images, Voyager 2 magnetic field observations, and dynamo simulations to estimate how the planets' magnetic fields might be configured today. However, to fully understand the planets' interiors, additional missions back to the ice giants are necessary.

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