Sunspots That Won't Go Away
The Sun's surface constantly generates magnetic structures that emerge, evolve, and decay over days, weeks, and months. Among these structures are active regions — patches of intense magnetic field that can produce solar flares and coronal mass ejections, the space weather events that disrupt satellites, power grids, and communications systems on Earth.
Most active regions last for a few days or weeks before their magnetic fields weaken and disperse. But some persist for more than a month, surviving multiple rotations of the Sun as it completes its roughly 27-day rotation. These long-lived active regions have always been of interest to solar physicists, but systematic data on just how unusual their behavior is has been lacking — until now.
A new study, built on observations from thousands of citizen scientists through NASA's Solar Active Region Spotter project, has produced that data, and the results are striking.
The Citizen Science Approach
The Solar Active Region Spotter project asked volunteers to examine pairs of images from NASA's Solar Dynamics Observatory and answer questions: Does this pair show the same active region? How have its characteristics changed? What is its structure?
Human pattern recognition is genuinely superior to algorithmic approaches for certain tasks involving complex, variable visual data. By aggregating observations from thousands of volunteers, the project was able to build a large, reliable dataset about how active regions evolve over time — a dataset that would have been expensive and time-consuming to build through purely automated means.
