In the early hours of Friday, a remarkable celestial event unfolded in Austria as a powerful solar storm, described by Geosphere Austria (formerly ZAMG) as the second strongest since 2005, illuminated the night sky with stunning displays of auroras. However, cloudy weather conditions hampered visibility in many areas, with the best sightings reported in Vorarlberg and Tyrol. Polar lights were even captured on various webcams, showcasing the phenomenon (source: foto-webcam.eu).
The solar storm began on Tuesday night, accompanied by a significant radiation burst that was observed centrally on the surface of the sun at 2:00 AM Wednesday. “Using so-called coronagraph images from space telescopes, it quickly became clear that the storm was moving towards Earth at high speed,” explained Eva Weiler from the Space Weather Office of Geosphere Austria. “The parameters derived from these images, especially the direction and speed of the storm, are crucial starting points for models that predict the arrival time of storms at Earth,” Weiler added. The Geosphere’s solar storm model accurately estimated the storm’s arrival time at Earth to within five hours, a figure well within acceptable error margins.
Finally, at 4:49 PM (Central European Summer Time) on Thursday, the solar storm reached Earth, resulting in dazzling auroras not only across Austria but also in other high to mid-latitude regions worldwide. Despite the strength of the auroras, visibility was compromised by rain and heavy cloud cover, with only brief breaks in the clouds reported. Erwin Filimon, chairman of the Astronomical Working Group of the Gahberg Observatory, noted that “the extremely strong auroras lasted all night.” He also indicated that due to heightened solar activity, there remains a significant likelihood of more auroras in Austria over the coming days and weeks.
Observations of the auroras were primarily made in northern and western Europe, including Slovenia and Italy. Colorful displays were also seen over large parts of Germany, particularly in Brandenburg, Saxony-Anhalt, Thuringia, and Bavaria. The phenomenon was not limited to Europe; it was also visible over the USA and the UK, with sightings reported in southern France above the Mediterranean.
Currently, this solar storm is about 20% weaker than the one experienced in May this year. According to Weiler, this geomagnetic storm is the second strongest in this solar cycle, following the May event, and the fourth strongest since the Halloween storm of 2003. Weiler assured that there are no expected impacts on the power grid, although disturbances may occur with the use of global navigation systems. The storm is anticipated to persist for several more hours on Friday, allowing for additional sightings of auroras in regions not exposed to daylight.
Weiler explained that the current solar cycle is more intense than the previous one, and it remains uncertain whether we have already reached the peak of solar activity or if it is still to come. Over the next few months, further solar storms could impact Earth, potentially leading to more auroras in Central Europe under favorable conditions.
Auroras result from the ongoing solar activity, which fluctuates in an approximately eleven-year cycle. The current cycle has just reached its maximum, a phase that lasts several years and is characterized by a higher frequency of solar eruptions. These colorful sky lights are generated when coronal mass ejections (CMEs) and massive solar plasma clouds collide with Earth’s magnetic field.
The US weather agency NOAA (National Oceanic and Atmospheric Administration) reported that the current storms have reached a category of G4. In contrast, the auroras visible across much of Germany in May were triggered by a G5 storm, the highest category.
