By combining European and U.S. space missions, scientists have achieved new insights into the sun’s most powerful activity
A wider view of the sun
The Sun rotates roughly once every 28 days, which means that from Earth, any active solar region can usually be observed for only about 2 weeks before it disappears from view on the far side.
For decades, this limitation prevented scientists from tracking the full life cycle of the Sun’s most energetic and potentially dangerous regions.
Now, thanks to the European Space Agency’s Solar Orbiter mission, launched in 2020, researchers can observe both the near and far sides of the Sun.
Orbiting the Sun every six months, Solar Orbiter offers a constantly shifting perspective that complements Earth-based observations and allows for much longer monitoring of solar activity.
Tracking a record-breaking active region
Between April and July 2024, Solar Orbiter observed one of the most active solar regions seen in the past 20 years. Known as NOAA 13664, the region became particularly significant in May 2024 when it rotated into view from Earth, triggering the strongest geomagnetic storms since 2003. These storms produced spectacular auroras that were visible far beyond their usual polar range, reaching as far south as Switzerland.
To fully understand the evolution of this region, an international research team combined Solar Orbiter data with observations from NASA’s Solar Dynamics Observatory, which continuously monitors the Sun from the Earth–Sun line. By merging data from both spacecraft, scientists were able to track NOAA 13664 almost continuously for 94 days.
This marks the longest continuous observational record ever created for a single solar active region, allowing researchers to study its complete life cycle from birth to decay.
Birth, growth and decay
The data reveal that NOAA 13664 first emerged on 16 April 2024 on the far side of the Sun. Over the following weeks, it grew in size and complexity as intensely magnetised plasma rose from within the Sun, distorting the solar surface. The region survived three full solar rotations before finally decaying after 18 July 2024.
As the region evolved, its magnetic field became increasingly tangled and complex. This buildup of magnetic energy eventually led to multiple eruptions, including the strongest solar flare observed in the past two decades, which occurred on 20 May 2024 while the region was still on the far side of the Sun.
Why solar storms matter on Earth
Active solar regions are the source of solar storms, which release enormous amounts of energy in the form of radiation, high-energy particles, and massive plasma clouds. When directed toward Earth, these storms can disrupt power grids, interfere with radio and GPS signals, increase radiation exposure for aircraft crews, and damage or destroy satellites.
The May 2024 storms caused widespread disruptions, including problems for digital agriculture. Satellite-guided machinery, drones, and sensor networks were affected, leading to lost working days and economic losses for farmers. In extreme cases, solar storms have even caused satellites to fall out of orbit, as happened in 2022 when dozens of newly launched satellites were lost.
By observing how NOAA 13664’s magnetic field developed over time, scientists gained valuable insight into how energy builds up and is released in superactive regions. This knowledge is crucial for improving space weather forecasting, which aims to predict when powerful solar storms may occur and how severe they might be.
Although precise predictions are not yet possible, these long-term observations represent a major step forward. Future missions, including ESA’s Vigil spacecraft, planned for launch in 2031, will focus specifically on monitoring space weather and protecting modern technology from the Sun’s most extreme behaviour.
