Two satellites launched by the European Space Agency have produced the clearest images ever taken of the Sun's outer atmosphere, and what they found there does not match the textbooks.
The ESA mission, called Proba-3, published its first science results last week in The Astrophysical Journal Letters. Andrei Zhukov of the Royal Observatory of Belgium, the lead author and principal investigator of the mission's main camera, reported that streams of charged particles called the slow solar wind are traveling at 250 to 500 kilometers per second near the Sun, roughly three to four times faster than the roughly 100 km/s that models predicted. The finding came from 57 artificial solar eclipses created by the spacecraft pair since July 2025, producing more than 250 hours of high-resolution video that gave scientists their first unobstructed look at the region within 0.1 solar radii of the Sun's surface.
Slow solar wind is the variable, gusty counterpart to the fast solar wind that blows steadily from dark patches on the Sun called coronal holes at roughly 480 km/s. Scientists have known about both streams for decades, but the slow wind's behavior near its source has been impossible to observe directly because the Sun's surface is blindingly bright from that distance. Zhukov's instrument, called ASPIICS, can see down to 70,000 kilometers from the Sun's surface, about one-tenth of a solar radius, because one of the two Proba-3 satellites casts a precisely controlled shadow over the other, mimicking a natural eclipse. The pair flies 150 meters apart, holding formation with millimeter precision.
"This is the innermost region of the solar wind's acceleration zone, and we've never been able to see it before," Joe Zender, ESA's Proba-3 project scientist, said in the agency's summary of the results. The surprise is not just the speed. Scientists had expected the slow wind to accelerate gradually as it moved outward from the Sun. The new data suggests something is adding energy much closer to the surface than previously thought.
The mechanism driving the slow solar wind involves the Sun's magnetic field lines, which constantly twist, reconnect, and recombine as they move through the corona. When a field line breaks and reconnects, it can fling a blob of plasma outward in what scientists call a streamer. The Proba-3 data suggests this process is more energetic and more widespread near the Sun than existing models assumed.
As SpaceDaily reported, the practical stakes are concrete. Every operational satellite in low Earth orbit experiences drag from the solar wind, and its exact magnitude affects orbital lifetime calculations and collision avoidance maneuvers. GPS satellites, which operate at roughly 20,000 kilometers altitude, depend on accurate space weather forecasts for timing corrections. Power grids use solar wind data to anticipate geomagnetic storms that can induce unwanted currents in transformers. If the baseline speed of the slow solar wind is off by a factor of three or four, every forecast built on that number is off too.
Space weather modeling groups at NASA, NOAA, and in Europe are likely to spend the next several years reconciling the Proba-3 observations with their existing frameworks. The paper published in The Astrophysical Journal Letters on March 9, 2026 represents one mission's early results; the broader scientific community will need to replicate the analysis and incorporate the findings into operational forecast models before the downstream effects become visible in commercial space weather products.
Proba-3 launched in December 2024 and has already demonstrated two world firsts: precision formation flying at this scale and sustained observation of the solar corona from inside the acceleration zone. The ESA team will continue collecting data through 2026, and scientists say the statistical sample will need to grow before the findings can be treated as settled.
The practical question is whether the existing models can be patched or whether they need to be rebuilt. The answer will matter to anyone who has a asset in orbit, a flight path over the poles, or a grid connection in a high-latitude region.
