iiinova — where your digital self keeps evolving

Bertrand Bonfond @berbonf.eurosky.social · 19/02/2026

If they are indeed the counterpart of the so-called "auroral beads" at Earth, they could be related to plasma instabilities in the magnetotail, participating to explosive reconfigurations of the magnetosphere called sub-storms.

Auroral beads as seen from the International Space Station. Credit: NASA

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Bertrand Bonfond @berbonf.eurosky.social · 19/02/2026

However, when zooming on individual strips, it becomes apparent that that this aurora is formed of a chain of patches rather than a uniform curtain. Similar auroral forms have been observed at Earth, and on other planets such as Jupiter or Saturn, suggesting that universal processes are at play.

Artistic views of the ultraviolet aurorae on Ganymede, based on Juno’s close-up observations from 7th July 2021. As Juno flew by Ganymede at high speed, its UV spectrograph could only acquire narrow strips, combined here to display the overall shape of the aurora (left). However, when zooming on individual strips (right), it becomes apparent that that this aurora is formed of a chain of patches rather than a uniform curtain. Similar auroral forms have been observed at Earth, as well as on other planets such as Jupiter or Saturn, suggesting that universal processes are at play. | © NASA/JPL-Caltech/SwRI/UVS/ULiège/Gusbin/Bonfond

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Bertrand Bonfond @berbonf.eurosky.social · 19/02/2026

On 7 July 2021, it was Ganymede's turn. The fly-by only lasted for ~15 minutes. Since Juno is a spinning spacecraft, its ultraviolet can only capture narrow strips across the moon, unveiling the auroras bits by bits. Combined together, they display the overall shape of the auroral ovals.

Artistic views of the ultraviolet auroras on Ganymede, based on Juno’s close-up observations from 7th July 2021. As Juno flew by Ganymede at high speed, its UV spectrograph could only acquire narrow strips, combined here to display the overall shape of the aurora. Credit: NASA/JPL-Caltech/SwRI/UVS/ULiège/Gusbin/Bonfond

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Bertrand Bonfond @berbonf.eurosky.social · 19/02/2026

Juno is a NASA spacecraft orbiting Jupiter since 2016. Its instruments are optimized to observe Jupiter itself and reveal its inner workings, its atmosphere and its magnetosphere. However, during its extended mission, it got the opportunity to perform close-up observations of some of its moons.

Artistic view of the Juno spacecraft near Jupiter. Credit: NASA

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Bertrand Bonfond @berbonf.eurosky.social · 19/02/2026

As a result from this interaction, electrons precipitate along Ganymede's magnetic field lines into the moon's thin atmosphere, forming bright auroras. Seen from the Hubble Space Telescope, these auroras form two blurry rings of light around the pole. uni-koeln.de/sites/uni/im...

Image of the UV auroras of Ganymede as viewed by the STIS instrument on board the Hubble Space Telescope, placed on top a visible image of Ganymede. The auroral emission are forming two ovals of UV emissions, one around each pole. The shape of these ovals, projected into the image, is materialized by dashed pink lines.

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Bertrand Bonfond @berbonf.eurosky.social · 19/02/2026

Ganymede is embedded into Jupiter's own magnetosphere, constantly swept by the plasma that rotates around the Giant Planet, forming a unique case of a magnetosphere inside a magnetosphere like a Russian doll.

Artistic representation of Ganymede orbiting Jupiter and being embedded into the Jovian plasma sheet, shown in yellow. Yellow arrow represent the direction of the plasma flow. The plasma sheet is tilted relative to Ganymede's orbital plane because the plasma is constrained by the tilted magnetic field of Jupiter. Arrows going through Jupiter materialize this tilt. Credit: B. Bonfond

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Bertrand Bonfond @berbonf.eurosky.social · 19/02/2026

Ganymede is the largest moon of the Solar System (it is larger than the planet Mercury), and the only one with its intrinsic magnetic field.

Artistic view of Jupiter, with its southern auroras shown in blue, along with its moons Io, Europa and Ganymede. The intrinsic magnetic field of Ganymede is represented by a dipolar grey shell. Credit: B. Bonfond

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Bertrand Bonfond @berbonf.eurosky.social · 02/04/2025

Frightening! But that's what happens when you stand too close to the motors during liftoff, I suppose...

A print screen of the CNN front page announcing that a billionaire and 3 cremates (sic) soared into space. It burns...

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Bertrand Bonfond @berbonf.eurosky.social · 28/02/2025

Mon fil BlueSky est volcanique aujourd'hui. 🌋

En haut un post avec une BD de Boulet dont la dernière case montre le Vésuve en éruption. En bas une photo de l'Etna en éruption avec un ciel étoilé en arrière plan, venant du compte Astronomy Picture of the Day.

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Bertrand Bonfond @berbonf.eurosky.social · 11/02/2025

Hi Celeste. On Feb 11th I see this when accessing this webpage from Belgium. It looks like before, right? Do you now see the same? Did they change it back?

Diversity and Inclusion webpage from AGU.org https://www.agu.org/Learn-About-AGU/About-AGU/Diversity-and-Inclusion .

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Bertrand Bonfond @berbonf.eurosky.social · 22/11/2024

So this is my word cloud! #PlanetaryScience 🔭 from: scholargoggler.com

Word could (a colorful word salad with font sizes corresponding to the occurrence rates) based on my published research from Google Scholar.

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Bertrand Bonfond @berbonf.eurosky.social · 17/09/2024

Nous sommes désormais plus de 10 millions sur Bluesky, et j’étais n°1 536 025 !

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