Audio collected during the Juno spacecraft’s last flyover of Ganymede — the largest moon of Jupiter and the Solar System — reveals a rather spooky experience. The news was released last Friday (17) at the American Geophysical Union Fall Meeting, where other findings from the Juno mission were shared.
On the 7th of June of this year, the Juno spacecraft performed its first flight over Ganymede and captured electromagnetic waves from the Jovian moon with its Waves instrument. When this data was changed to the audio track, it was discovered a strange sound filled with alien noises. Listen up:
The mission’s principal investigator, physicist Scott Bolton of the Southwest Research Institute, said you can hear an abrupt shift to higher frequencies at the midpoint of the recording. “Which represents entry into a different region of Ganymede’s magnetosphere,” he added.
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Analyzing other worlds from their respective sounds helps to notice details that might otherwise go unnoticed. A number of other probes sent to planets in the Solar System, as well as Voyager, also collected these audios.
Possible explanation for the sounds of Ganymede
The moon Ganymede draws attention for its size — larger than the planet Mercury — and its core responsible for making this world the only natural satellite in the Solar System to have a magnetic field. Furthermore, the moon may harbor a liquid ocean just below its icy crust.
On Juno’s last approach to Ganymede, the probe was 1,038 km away from the moon’s surface, at a speed of 67,000 km/h, as it makes its 34th trip around Jupiter. Scientists are still studying to understand the newly published audio, but they have an idea of what it might be.
According to physicist and astronomer William Kurth, from the University of Iowa in Iowa City and co-investigator of the Waves apparatus, it is possible that the change in frequency right after the approach is due to the transition from the night side to the day side of Ganymede. But the probe didn’t just look at the moon.
Thanks to Juno’s observations, researchers created a detailed map of Jupiter’s magnetic field, which took 32 orbits to complete. A magnetic anomaly at the planet’s equator, called the Great Blue Spot, has been observed.
The map indicated that Jupiter’s magnetic field has changed over the past five years and that powerful winds in the planet’s atmosphere have been pushing the anomaly eastward at a rate of 4 cm/s. Studying the gas giant’s magnetosphere allows us to understand part of what happens in its core.
The data suggested that the dynamo — the mechanism responsible for generating the magnetic field in celestial bodies — is produced by a deep layer of metallic hydrogen around Jupiter’s core. The team of scientists also analyzed the turbulence in its atmosphere.
The vortices of its atmosphere resemble phytoplankton explosions in Earth’s oceans, which led oceanographer Lia Siegelman of the Scripps Institution of Oceanography to relate these movements. According to her, these patterns arise spontaneously and can last for a long time.
Juno’s data also revealed a startling insight into Jupiter’s system: the planet’s thin main ring, formed by dust released by its moons Metis and Adrastea. The probe registered the structure from within, with part of the constellation Perseus in the background.
The Juno mission has been extended until June 2025, and it is hoped that, until then, the spacecraft will continue to provide crucial information for understanding the intriguing system of Jupiter and its many moons.