Astronomers Solve Saturn's Decades-Long Spin Mystery Using James Webb Space Telescope
Researchers finally solved the 20-year puzzle of why Saturn appeared to change its rotation rate by discovering that powerful winds driven by the planet's aurora create the illusion, not actual changes in spin.
The Mystery Unraveled
A decades-old mystery about Saturn has finally been solved thanks to the James Webb Space Telescope. Scientists discovered that Saturn's changing "rotation rate" was never caused by the planet speeding up or slowing down, but by powerful winds high in its atmosphere.
How the Discovery Was Made
Researchers at Northumbria University led by Tom Stallard used JWST to observe Saturn's northern aurora continuously for an entire Saturnian day (10 hours and 33 minutes). The key to their breakthrough was a molecule called trihydrogen cation (H₃⁺). This molecule glows in infrared light and acts like a natural thermometer for the upper atmosphere. By tracking its glow, scientists created high-resolution maps of temperature and particle density across Saturn's poles.
The Self-Sustaining Cycle
Webb's unprecedented observations revealed that Saturn's northern lights actively heat the atmosphere, creating winds that generate electrical currents, which then power the aurora all over again in a self-sustaining cycle. This feedback loop explains why earlier measurements by NASA's Cassini spacecraft in 2004 suggested the planet's rotation rate was changing—it was actually atmospheric winds creating the illusion.
Broader Implications
The findings, published in the Journal of Geophysical Research: Space Physics, have implications beyond Saturn. Understanding how auroras drive atmospheric dynamics could reveal similar processes on other planets, including those orbiting distant stars. Scientists note this discovery may help explain mysteries in exoplanet atmospheres and transform how researchers study planetary systems throughout the universe.