In May 2024, Earth was slammed by the worst geomagnetic storm in more than 20 years, which disrupted radio signals, power grids, and satellites. The storm originated from an active solar region known as NOAA 13664, which emitted a slew of solar flares in our direction. Today, scientists revealed that they observed this region for 94 days, watching it evolve from birth until decay.
An international team of researchers tracked the active solar region using the Solar Orbiter spacecraft, a joint NASA and European Space Agency mission that orbits the Sun on an elliptical path to capture the closest-ever images of our host star. This allowed the team to observe NOAA 13664 almost continuously for a record-breaking period of time, marking the longest series of images ever created of a single active region on the Sun.
“It’s a milestone in solar physics,” Ioannis Kontogiannis, a solar physicist at the Swiss Federal Institute of Technology Zurich (ETH Zurich) and lead author of a new study published in Astronomy & Astrophysics, said in a statement.
A storm is coming
Active regions on the Sun are areas with an especially strong, tangled magnetic field, and they are known to release bursts of high-energy radiation (solar flares) and violent eruptions of plasma (coronal mass ejections). If those eruptions are blasted in Earth’s direction, it can signal big trouble for our modern-day technology.
On May 10, 2024, a G5, or extreme, geomagnetic storm hit Earth as a result of large expulsions of plasma from the Sun’s corona. The G5 storm caused some deleterious effects on Earth’s power grid and some spectacular auroras seen across much of the globe. The storm also increased atmospheric density in low Earth orbit by up to an order of magnitude, which in turn caused atmospheric drag that affected satellites.
Scientists traced this geomagnetic storm back to active region NOAA 13664. Active solar regions are difficult to observe over long periods of time as the Sun rotates on its axis once every 28 days. That means active regions stay in our view for around two weeks at a time before they disappear on the other side of the Sun.
“Fortunately, the Solar Orbiter mission…has broadened our perspective,” Kontogiannis said. Using the Solar Orbiter spacecraft, the team observed the active region behind the geomagnetic storm from its birth on April 16, 2024, on the far side of the Sun until its decay after July 18, 2024.
By doing so, the team tracked three solar rotations for the first time ever, watching as the magnetic field of the active region grew more complex over time. The researchers observed the formation of an intertwined magnetic structure right before the Sun released the strongest solar flare in over 20 years.
“We live with this star, so it’s really important we observe it and try to understand how it works and how it affects our environment,” Kontogiannis said. “It’s a good reminder that the sun is the only star that influences our activities.”