The solar wind is a stream of charged particles constantly blown off the Sun's surface, filling the entire solar system. It's not like a steady breeze: it has eddies, gusts, and calm patches. Scientists call this turbulence. Turbulence is what determines how the wind heats up and speeds up on its journey from the Sun to Earth.

Over 25 orbits around the Sun, the Parker Solar Probe gathered data on how this wind behaves at different stages of the solar cycle. It turns out that the strength of turbulence depends on where exactly the stream originated. If it comes from a coronal hole, a region with an open magnetic field of a single polarity, the wind is more turbulent and hotter. If the source is an active region with a complex tangle of magnetic fields, the wind is calmer.

This discovery bridges two worlds: what we see on the Sun through a telescope and what the probe feels in flight. Now we can predict what the solar wind will be like at Earth by looking at the Sun's magnetic field map.