Now, thanks to NASA’s Solar Dynamics Observatory, a team has identified flickering loops in the solar atmosphere (corona) which seem to indicate that the Sun is about to trigger a large eruption.
These warning signs could help NASA and other stakeholders protect astronauts and technology, both in space and on Earth, against dangerous space weather conditions.
Led by heliophysicist Emily Mason of Predictive Sciences Inc. in San Diego, California, the team studied arc-shaped structures, called coronal loops, along the edge of the sun. Coronal loops come from the active regions of the sun, driven by magnetism, where solar flares also originate.
Flashing loops as an indicator of an intense solar flare
The team observed coronal loops near 50 intense solar flares and analyzed variations in their brightness in extreme ultraviolet light in the hours before a flare, compared to those of loops above regions without flares. Like flashing warning lights, loops above regions with flares showed much greater variations than those above regions without flares.
“We found that some of the extreme ultraviolet light above active regions flashes erratically for a few hours before a solar flare occurs,” Mason said. “These results are very important for understanding flares and may improve our ability to predict weather hazards in space.”
NASA’s Solar Observatory observes how coronal loops flicker before large flares, and their analysis is potentially useful.
-The results, published in the journal Astrophysical Journal Letters and presented on January 15, 2025 during a press conference organized as part of the 245th meeting of the American Astronomical Society, also suggest that the flicker peaks earlier for the strongest flares. However, the team specifies that further observations are necessary to confirm this link.
The four panels of this video show brightness changes in coronal loops at four different wavelengths of extreme ultraviolet light (131, 171, 193 and 304 angstroms) before a solar flare in December 2011. The images were taken by the Atmospheric Imaging Assembly (AIA) at NASA’s Solar Dynamics Observatory and processed to reveal the flicker of the coronal loops. Credit: NASA / Solar Dynamics Observatory / JHelioviewer / E. Mason
Mason and his colleagues believe that measuring brightness variations in coronal loops could provide more accurate alerts than these methods, locating impending eruptions 2-6 hours in advance with 60-80% accuracy.
“The solar corona is a dynamic environment and each solar flare is like a snowflake: each flare is unique,” said team member Kara Kniezewski, a graduate student at the Air Force Institute of Technology and lead author of the article. We found that looking for periods of “chaotic” behavior in coronal loop emission, rather than specific trends, provides a much more consistent measurement and can also be correlated with the intensity of an eruption.
Scientists hope their findings about coronal loops can one day be used to protect astronauts, spacecraft, power grids and other assets from the harmful radiation that accompanies solar flares. For example, an automated system could look for changes in the brightness of coronal loops in real-time images from the Solar Dynamics Observatory and issue alerts.
Article reference:
Kara L. Kniezewski et al, 131 and 304 Å Emission Variability Increases Hours Prior to Solar Flare Onset, The Astrophysical Journal Letters (2024). DOI: 10.3847/2041-8213/ad94dd
