The solar corona lives its own turbulent life. Magnetic fields here are governed by the motions of the dense surface — the Sun's photosphere — but occasionally they rewrite the magnetic pattern themselves. During flares, coronal loops — plasma arches — twist up and reconnect. Then they start to unwind, and the twist doesn't vanish; instead, it flows downward.
Think of a rubber band. Twist one end hard and let go — the twist travels to the other end. A magnetic loop works the same way: after a flare, it transfers its rotation to its footpoints, which lie far from the action. There, currents intensify, and around an old sunspot a dark scar emerges — a zone of strengthened magnetic field.
Even Galileo Galilei sketched these spots, and Joseph von Fraunhofer devised a way to split starlight into colors and study its composition. Now, by combining observations with mathematical modeling, astrophysicists have uncovered the hidden mechanism: a magnetic vortex migrates from the corona into the photosphere. This explains puzzling changes after solar storms — and shows that stars live by continually reshaping their magnetic portraits.
An ordinary sunspot is often larger than Earth, and the dark scar around it can add several thousand more kilometers — as if a wound on the star's surface were healing.