March 27, 2026
JWST solves decades-long mystery about why Saturn appears to change its spin
edited by Gaby Clark, reviewed by Robert Egan
Abstract
This article explores the findings of researchers who used the James Webb Space Telescope to provide insights into the long-standing mystery of Saturn's apparent changing spin rate and the atmospheric dynamics that drive this phenomenon.
Introduction
Saturn has puzzled scientists for many years. Measurements taken by NASA's Cassini spacecraft in 2004 suggested the planet's rotation rate was slowly changing over time—yet this should not have been possible, as a planet cannot simply speed up or slow down its spin.
In 2021, a study led by Tom Stallard, Professor of Planetary Astronomy at Northumbria University, showed that the mystery did not actually involve Saturn's rotation at all. Instead, the apparent changes were being driven by winds in the planet's upper atmosphere, which were producing electrical currents that created the misleading auroral signal.
Research Findings
Recent observations by the James Webb Space Telescope (JWST) identified the driving forces behind Saturn's atmospheric wind patterns and their impact on the planet's magnetic field dynamics.
- The study established that Saturn's auroras are not just a visual display but actively influence atmospheric heating.
- The data also aligned with predictions from previous computational models regarding temperature distributions across Saturn's auroral region.
Conclusion
The research conducted provides essential insights into the influence of planetary auroras on their atmospheres and magnetic environments. As researchers continue to examine further implications from the findings, the collaborative efforts across institutions will play a crucial role in advancing our understanding of gas giant planets.
More information
Tom S. Stallard et al, JWST/NIRSpec Reveals the Atmospheric Driver of Saturn's Variable Magnetospheric Rotation Rate, Journal of Geophysical Research: Space Physics (2026). DOI: 10.1029/2025ja034578
"What we are seeing is essentially a planetary heat pump... This result changes how we think about planetary atmospheres more generally." - Professor Tom Stallard
