Jupiter is well-known for the huge aurorae that happen close to the planet’s polar areas, the brightest and strongest within the Photo voltaic System. Very similar to aurora right here on Earth, these shimmering lights are the results of interplay between the planet’s magnetic discipline and photo voltaic wind. Not like Earth’s, although, Jupiter’s largest moons – Io, Europa, and Ganymede (aka. the Galileans) – depart their very own auroral signatures within the planet’s ambiance. These induced aurorae are often called “satellite tv for pc footprints” and observe how every moon interacts with Jupiter and the native area surroundings.
Whereas scientists have noticed how Io, Europa, and Ganymede create satellite tv for pc footprints in Jupiter’s ambiance, Callisto has remained a little bit of an outlier. Regardless of a number of makes an attempt utilizing the Hubble House Telescope (HST), signatures attributable to Callisto remained elusive. Because of NASA’s Juno mission, which achieved orbit round Jupiter in 2016, Callisto’s satellite tv for pc footprint has lastly been discovered. In a recent study, a world workforce of scientists offered proof of those polar gentle signatures in Jupiter’s ambiance for the primary time.
The workforce was led by Jonas Rabia of the Institut de Recherche en Astrophysique et Planétologie (IRAP). He was joined by researchers from the
Institut Origines on the Laboratoire d’Astrophysique de Marseille (LAM), the Laboratoire d’Instrumentation et de Recherche en Astrophysique (LIRA), Institut Supérieur de l’Aéronautique et de l’Espace (ISAE), the Laboratory for Planetary and Atmospheric Physics (LPAP), the Minnesota Institute for Astrophysics (MIfA), the Southwest Analysis Institute (SwRI), and NASA’s Goddard House Flight Middle.
Whereas Juno has offered close-up views of Jupiter’s aurorae, capturing Callisto’s footprint offered a significant problem. Along with being faint, Callisto’s auroral signature sometimes resides above the brighter area the place Jupiter’s aurorae are displayed (the primary auroral oval). To measure Callisto’s footprint, the science workforce wanted to picture Jupiter’s polar area solely after the primary auroral oval moved apart. The spacecraft additionally wanted to cross the magnetic discipline line linking Callisto and Jupiter for its devices to detect the auroral signature.
This included its Magnetometer(MAG), Jovian Auroral Distributions Experiment (JADE), and Jovian Energetic Particle Detector Instrument (JEDI). As luck would have it, each of those occasions occurred in September 2019 when an enormous high-density photo voltaic stream hit Jupiter’s magnetosphere, inflicting it to shift to decrease latitudes. That is much like how photo voltaic storms usually push the northern lights to extra southern latitudes. This revealed Callisto’s auroral footprint and offered important information on the energetic particles, electromagnetic waves, and magnetic fields related to the interplay.
This confirms that each one 4 Galilean moons depart lasting indications of their passage by way of Jupiter’s magnetic discipline. The paper on the invention, “In situ and remote observations of the ultraviolet footprint of the moon Callisto by the Juno spacecraft,” was printed within the journal Nature Communications on Sept. 1st, 2025.
Additional Studying: NASA
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