After years of mystery, scientists discover Saturn's secret.
Astronomers have finally solved one of the most perplexing mysteries about Saturn , after observations by the James Webb Space Telescope revealed that the changes observed in the planet's rotation rate were not due to actual acceleration or deceleration, but rather to a complex phenomenon related to the aurora borealis and winds in its atmosphere. According to a study published in the Journal of Geophysical Research: Space Physics, the aurora borealis at Saturn's north pole drives a continuous cycle of heating, winds, and electric currents, which alters the signals used to measure the planet's rotation speed, giving the false impression that its rotation rate changes over time.
A mystery that lasted for years
The scientific confusion began decades ago, but it was renewed in 2004 when data from NASA's Cassini probe showed that Saturn's rotation speed appeared different than expected. This was difficult to explain because giant planets don't change their rotation rates over short periods. In 2021, a research team led by Professor Tom Stallard of Northumbria University in the UK suggested that the cause wasn't the planet itself, but rather winds in its upper atmosphere that affect the electrical signals associated with auroras.
James Webb settles the debate
To test this hypothesis, the researchers used the James Webb Telescope to observe Saturn's northern auroral region over a full day of the planet's life. The team relied on measuring the light emitted by a molecule known as the "trivalent hydrogen ion," which is a natural indicator of temperature in the upper atmosphere. The data allowed them to produce the most accurate maps to date of temperatures and charged particle density in the polar region. The results showed that the energy released by the aurora borealis heats specific areas of the atmosphere, generating strong winds which in turn produce electrical currents that help feed the aurora borealis itself, in a continuous, self-sustaining cycle.
More than just pretty lights
Professor Stallard said that what is happening is similar to a "planetary heat pump," where the aurora heats the atmosphere, generating winds, which in turn produce electrical currents that feed the aurora back again. He added that these observations finally provided the evidence that scientists had been lacking to understand the cause of the apparent changes in Saturn's rotation rate and close a file that had been ongoing for decades.
Significances that go beyond Saturn
The significance of the discovery is not limited to Saturn alone, as the results indicate a close relationship between the atmosphere and the planet's magnetic field, which may also occur in other worlds within and outside the solar system. Researchers believe that understanding these interactions may help in the future to uncover new mechanisms that govern the atmospheres of distant planets and their relationship to the space surrounding them, opening up new horizons for studying the evolution of planets and habitable environments in the universe.
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