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This artist's conception shows the boundary in the Sun's atmosphere where the speed of the outward solar wind becomes faster than the speed of magnetic waves. The area appears to shift between spiky and frothy, and is the point of no return for material that escapes the Sun's magnetic grasp. Deep dives into the Alfvén surface using NASA's Parker Solar Probe combined with far-away measurements, have allowed scientists to track the evolution of this structure throughout the solar cycle and produce a map of this previously uncharted territory.