Photo: NASA, ESA, CSA, Jupiter ERS Team; image processing by Ricardo Hueso (UPV/EHU) and Judy Schmidt
The moons of Jupiter may influence the giant planet’s powerful auroras by disturbing its magnetic environment, scientists say. The discovery was made using observations from the James Webb Space Telescope and reported by Space.com.
Researchers detected a cold spot in Jupiter’s atmosphere and an unusually rapid increase in the density of charged particles. According to Katy Knowles, a PhD student at Northumbria University in the UK, Jupiter’s moons constantly interact with the planet’s magnetic field and surrounding plasma.
This interaction causes high-energy particles to travel along magnetic field lines and collide with Jupiter’s atmosphere, producing traces in the auroras that correspond to the moons’ orbital paths.
Auroras on Jupiter form similarly to those on Earth: charged particles from the solar wind are captured by the planet’s magnetic field and guided toward the poles, where they collide with atmospheric atoms and molecules, making them glow. However, the four largest Galilean moons — Io, Europa, Ganymede and Callisto — can leave distinctive marks in these auroras.
One key factor is the Io plasma torus, a ring of charged particles produced by intense volcanic activity on Io — the most volcanically active body in the Solar System. These particles orbit Jupiter and interact with its magnetic field. As the moons move through this plasma environment, they can direct ions toward the planet’s atmosphere, strengthening auroral emissions and generating electric currents.
In 2023, researchers Henrik Melin and Tom Stallard from Northumbria University used the James Webb telescope to capture images of Jupiter’s auroras. Out of five images, four appeared normal, but one revealed a distinct cold patch beneath an auroral footprint linked to Io.
While the surrounding auroral region had temperatures of about 493 °C, the cold spot measured around 295 °C. At the same time, the density of ions feeding the aurora — especially the triatomic hydrogen ion H₃⁺ — was about three times higher than usual, and within the cold patch it could vary by up to 45 times.
Scientists also observed extreme fluctuations in temperature and particle density occurring within minutes, indicating that the flow of energetic electrons hitting Jupiter’s atmosphere can change very rapidly.
Jupiter’s auroras are the most powerful in the Solar System, making them an important natural laboratory for studying interactions between planetary magnetic fields and their moons.
