New research undermines hypothesis on mystery behind Jupiter's unusual core

Scientists from Durham University in the UK, along with experts from NASA, SETI, and the University of Oslo, have challenged the long-standing theory that Jupiter’s “fuzzy” core was formed by a massive ancient collision.

Their findings were published in the Monthly Notices of the Royal Astronomical Society (MNRAS) and reported on in an article published on the Phys.Org platform. 

According to the researchers conclusion, their results do not support the hypothesis that Jupiter's dilute core was produced by a single dramatic impact but instead suggest that it is the result of how the growing planet absorbed heavy and light materials as it formed and evolved.

Jupiter, the largest planet in our solar system, hides an intriguing mystery at its center. Instead of a sharply defined core as once believed, its inner region gradually merges with surrounding hydrogen-rich layers — a structure known as a dilute core.

The origin of this diffuse core has puzzled scientists ever since NASA’s Juno spacecraft discovered it in 2016 after a five-year journey to the gas giant. Juno’s groundbreaking mission, which transformed our understanding of Jupiter, is set to conclude in September 2025.

For years, scientists speculated that such a core resulted from a catastrophic event — a giant protoplanet allegedly slammed into Jupiter, mixing its inner layers.

To verify this idea, the research team ran a series of advanced supercomputer simulations at the DiRAC COSMA facility in Durham, using SWIFT software and a new material-mixing model.

The outcome was surprising: even under extreme impact conditions, none of the simulated collisions produced a stable fuzzy core. Instead, displaced rock and ice quickly sank back, restoring a well-defined core boundary.

“Such impacts do shake Jupiter all the way to its center, but not in the way required to explain its current structure,” explained lead author Dr. Thomas Sandnes.

The team concluded that Jupiter’s diluted core formed gradually during its growth, as heavy and light elements settled differently over time — not through a single cataclysm.

Interestingly, Jupiter isn’t unique in having a dilute core, as recent research has revealed that Saturn possesses a similar structure.

Dr. Luis Teodoro of the University of Oslo explained that this realization strengthens the idea that these structures are not the result of rare, extremely high-energy impacts but instead form gradually during the long process of planetary growth and evolution.

These findings may also shed light on the interiors of the numerous Jupiter- and Saturn-sized exoplanets discovered around distant stars. If dilute cores are not the product of rare, violent impacts, it suggests that many of these distant giants could have similarly complex inner structures.

Co-author Dr. Jacob Kegerreis emphasized, "Giant impacts are a key part of many planets' histories, but they can't explain everything! This project also accelerated another step in our development of new ways to simulate these cataclysmic events in ever greater detail, helping us to continue narrowing down how the amazing diversity of worlds we see in the solar system and beyond came to be."

By Nazrin Sadigova