Electron storm causes auroral emissions on Mercury’s surface!

The interaction between the solar wind and a planet’s intrinsic magnetic field leads to a variety of responses within the magnetosphere it forms. As with the Earth, but on much faster timescales, Mercury’s magnetosphere is known to involve fundamental processes leading to rapid reconfigurations of the magnetosphere releasing plasma and energy. During the magnetospheric cycle that results from this interaction, charged particles are accelerated, transported, lost or recycled in the magnetosphere. Electrons in particular can precipitate and induce auroral X-ray fluorescence emissions on Mercury’s surface.

The BepiColombo mission, whose third close flyby of Mercury has just taken place in June 2023, is equipped with state-of-the-art plasma instrumentation to study the properties of charged particles in Mercury’s magnetosphere, and in particular, 50 years after the Mariner 10 mission, those of thermal and suprathermal electron populations.

A research team including scientists from IRAP (CNRS-INSU, Université de Toulouse III and CNES), has analyzed data collected during the first Mercury flyby in October 2021 by the Mercury MEA electron analyzers (1) supplied by IRAP (2) , and revealed for the first time multiple, impulsive injections of suprathermal electrons onto closed magnetic field lines that eventually precipitate to Mercury’s surface, in connection with the probable development of magnetic substorm-type activity. These observations underline that electron injections and the resulting energy-dependent magnetic drift are a universal mechanism now documented throughout the Solar System. This mechanism generates different types of aurora now observed on all magnetized planets except Neptune, as well as above the crustal magnetic fields of the Martian crust, despite the differences in structure and dynamics of planetary magnetospheres.

Multiple, impulsive observations of multiple injections of suprathermal electrons that precipitate along magnetic field lines on Mercury’s surface and create auroral X-ray fluorescence emissions. © Sae Aizawa


  1. Mercury Electron Analyzer
  2. Institut de Recherche en Astrophysique et planétologie (IRAP – OMP)

Further Resources

IRAP Contact

  • Nicolas André, nicolas.andre@irap.omp.eu

More news

First solar wind data for JENI onboard JUICE!

On June 5, less than two months after the successful launch of the ESA spacecraft JUICE (JUpiter Icy moon Explorer) towards Jupiter, the Jupiter Energetic Neutrals and Ions (JENI) sensor […]

Mars: new evidence of an environment conducive to the emergence of life

Using data from NASA’s Curiosity rover, scientists at the CNRS, Université Toulouse III – Paul Sabatier and Université Claude Bernard Lyon 1, with the participation of CNES, have discovered patterns […]

One month after lift-off, the Euclid mission reveals its first observations

One month after Euclid’s launch, the European Space Agency (ESA), in collaboration with the Euclid consortium, unveils the first observations captured by the satellite as it completes its in-flight acceptance […]