A difficult-to-observe region of the sun is yielding a surprise

The European Space Agency’s Proba-3 mission has produced observations suggesting that slow solar wind in the sun’s inner corona moves far faster than expected. According to the supplied Space.com report, researchers studying images from the eclipse-simulating spacecraft found gusts moving three to four times faster than earlier assumptions. The finding matters because the inner corona is one of the hardest places in solar physics to observe directly, despite being central to understanding how the sun sheds material into space.

Solar wind is a constant outflow of charged particles from the sun. Scientists have long distinguished between fast solar wind, which can reach about 480 miles per second and is associated with coronal holes, and slower wind emerging closer to the sun’s surface. The slow solar wind studied here had previously been known to blow at around 60 miles per second, according to the source text. Proba-3’s data indicate that this picture may have underestimated how quickly that material can move in the inner corona.

The result is significant not because it overturns everything known about solar wind, but because it provides new information from a region that has been unusually difficult to measure. If the slow wind accelerates earlier and more forcefully than expected, models of how energy and plasma move through the corona may need revision.

Why Proba-3 is able to see what is usually hidden

The Proba-3 mission is notable in its own right. The report describes it as a duo of satellites flying in formation to simulate a solar eclipse. That arrangement lets the mission block the intense brightness of the sun’s disk and observe the faint corona more clearly. Ordinarily, the glare of the sun makes this region extremely challenging to study except during rare natural eclipses or through specialized instruments.

That is why the new data stand out. The inner corona is precisely where key questions about solar wind formation and acceleration remain unresolved. Being able to observe that zone more effectively gives researchers access to a part of the sun’s atmosphere that has often sat between theoretical models and limited observational evidence.

The report quotes Andrei Zhukov of the Royal Observatory of Belgium saying that in the inner corona, scientists saw slow solar wind gusts moving three to four times faster than expected. Even framed cautiously, that is the kind of statement that draws attention because it points to a mismatch between prior assumptions and newly available measurements.