The Sun rotates on its axis approximately every 28 days, limiting Earth-based observation of active solar regions to two weeks at a time before they rotate out of view. The European Space Agency’s (ESA) Solar Orbiter mission, launched in 2020, has extended this observational capacity by orbiting the Sun every six months and observing its far side.
Observing Active Region NOAA 13664
Between April and July 2024, Solar Orbiter monitored NOAA 13664, an active region. In May 2024, as NOAA 13664 rotated into view from Earth, it initiated geomagnetic storms, identified as the strongest since 2003. These storms resulted in visible aurora borealis events, observable in regions as far south as Switzerland.
Combined Data for Continuous Tracking
To enhance understanding of the formation, development, and effects of such solar regions, an international research team led by Ioannis Kontogiannis and Louise Harra from ETH Zurich and IRSOL combined observational data. This involved integrating data from Solar Orbiter (monitoring the far side of the Sun) with data from NASA's Solar Dynamics Observatory (observing the near side from the Earth–Sun line).
This data integration allowed for near-continuous tracking of region NOAA 13664 for 94 days. This duration represents the longest continuous imaging series recorded for a single active region to date. Researchers documented the emergence of NOAA 13664 on April 16, 2024, on the far side of the Sun, and subsequently tracked its evolution until its dissipation after July 18, 2024.
Solar Storm Mechanics and Terrestrial Impacts
Active regions on the Sun are characterized by strong and complex magnetic fields, which develop when highly magnetized plasma reaches the solar surface. These conditions frequently lead to violent eruptions, known as solar storms. Solar storms release significant amounts of electromagnetic radiation (flares), eject plasma from the Sun's atmosphere, and emit high-energy particles into space.
Beyond generating auroras, solar storms can affect terrestrial technology and infrastructure. Reported impacts include power outages, disruptions to communication signals, increased radiation exposure for aircraft crews, and satellite malfunctions. An example occurred in February 2022, when 38 out of 49 Starlink satellites were lost shortly after launch due to a geomagnetic storm. Disruptions to railway signals and agricultural systems, including satellite, drone, and sensor signals, have also been attributed to solar activity, impacting operational efficiency and leading to economic losses. The Sun's activity is a factor influencing Earth-based systems and human activities.
Advancements in Space Weather Forecasting
Observations allowed researchers to track three solar rotations of NOAA 13664, detailing the development of its magnetic field and its increasing complexity over time. This culminated in the release of a significant flare on the far side of the Sun on May 20, 2024, identified as the strongest in the preceding twenty years.
These findings contribute to improving the understanding of solar storms and their potential effects on Earth, with the objective of enhancing space weather forecast accuracy. This improved forecasting aims to provide better protection for sensitive modern technologies. Indicators such as highly complex magnetic fields in solar regions suggest a potential for significant energy release in the form of solar storms.
Current predictive capabilities do not allow for accurate forecasting of the precise magnitude, frequency, or timing of solar eruptions. In response, ESA is developing a new space probe, Vigil, specifically for advancing space weather understanding, with a planned launch in 2031.