The Solar Dynamics Observatory was able to capture the oddity that spacecraft rarely observed - a dark string surrounding the active region on the Sun (October 29-31, 2017). Solar filaments are clouds of charged particles floating above a star and held by magnetic forces.
Usually the threads seem uneven and elongated. Only at certain moments it turns out to fix them in the form of a circle.
The dark area on the left is the coronal hole, the magnetically opening solar patch. For science, this event does not have remarkable value, but it is interesting because of its rarity. Review conducted in ultraviolet light.