Scientists have achieved a milestone in solar observation by tracking an exceptionally active region on the Sun, NOAA 13664, almost continuously for 94 days using data from two spacecraft. This region, which emerged in April 2024, triggered the strongest geomagnetic storms since 2003 and caused widespread auroras. The extended monitoring reveals how complex magnetic fields drive solar storms with real-world impacts.
In a breakthrough for solar physics, researchers combined observations from the European Space Agency's Solar Orbiter, launched in 2020, and NASA's Solar Dynamics Observatory to follow the evolution of NOAA 13664. This active region first appeared on the Sun's far side on April 16, 2024, and was tracked through its growth, twists, and decay until after July 18, 2024, spanning three full solar rotations.
The spacecraft's complementary views allowed unprecedented coverage: Solar Orbiter observed hidden areas during its six-month orbit, while the Earth-orbiting observatory monitored the Sun-facing side. "This is the longest continuous series of images ever created for a single active region: it's a milestone in solar physics," said Ioannis Kontogiannis, a solar physicist at ETH Zurich and the Istituto ricerche solari Aldo e Cele Daccò in Locarno.
NOAA 13664's intense magnetic fields led to dramatic events, including the most powerful solar flare in two decades on May 20, 2024, on the Sun's far side. When it rotated into Earth's view in May, it unleashed geomagnetic storms that produced auroras visible as far south as Switzerland. "This region caused the spectacular aurora borealis that was visible as far south as Switzerland," noted Louise Harra, professor at ETH Zurich and director of the Davos Physical Meteorological Observatory.
Beyond visual spectacles, these storms disrupted modern technologies. In May 2024, satellite signals, drones, and sensors failed, affecting digital agriculture and causing crop losses for farmers. Harra highlighted risks like railway signal malfunctions: "Even signals on railway lines can be affected and switch from red to green or vice versa. That's really scary." Earlier, in February 2022, solar activity destroyed 38 of 49 Starlink satellites shortly after launch.
The study, published in Astronomy in 2025, underscores the Sun's influence on Earth. "It's a good reminder that the sun is the only star that influences our activities," Kontogiannis added. Researchers aim to improve forecasts, with ESA's Vigil mission set for 2031 to enhance space weather predictions and protect infrastructure from future eruptions.
