JWST Solves Saturn's 40-Year Spin Mystery

Scientists at Northumbria University have determined that Saturn's apparent changing rotation rate is an atmospheric illusion rather than a change in spin ^[1].

This discovery resolves a scientific puzzle that has persisted for decades ^[2]. By identifying the mechanism behind the planet's perceived instability, researchers can now better understand the complex interactions between a gas giant's interior, and its upper atmosphere.

Observations from the James Webb Space Telescope (JWST) show that the phenomenon is caused by atmospheric winds driven by auroral heating [1, 3]. These winds generate electrical currents that create a self-sustaining heat engine [3, 4]. This process makes the planet's spin appear to vary, although the actual rotation of the planet remains constant ^[3].

The breakthrough was made possible by the precision of the JWST's NIRSpec instrument. The resulting aurora maps are 10 times sharper than the data previously collected by the Cassini spacecraft ^[4]. This increased resolution allowed the team to pinpoint the relationship between the auroras, and the wind patterns that mislead observers.

For 40 years, the shifting rotation rate of Saturn had remained a mystery to astronomers ^[4]. Previous theories struggled to explain why the planet's spin seemed to fluctuate over time. The new data confirms that the movement is not a physical shift in the planet's core, but a result of high-altitude weather patterns [1, 3].

The findings emphasize the role of auroral heating in driving the dynamics of the upper atmosphere. The interaction between the solar wind and Saturn's magnetic field triggers the heating, which in turn powers the winds that create the spin illusion [3, 4].