🌟 The slow solar wind much faster than expected!

The Sun never ceases to surprise us. Recent measurements reveal that the slow solar wind, which emerges near the surface of our star, can blow much stronger than expected. A team of researchers has detected gusts reaching speeds three to four times greater than previous estimates. This unexpected finding challenges our understanding of this stream of particles that bathes the entire Solar System.

The solar wind is a constant flow of charged particles ejected from the Sun. There are two main types: the fast wind, originating from coronal holes, zips along at nearly 300 miles per second (480 km/s). The slow wind, on the other hand, was estimated at about 62 miles per second (100 km/s). But images from the European Space Agency's Proba-3 mission reveal that this slow wind can reach 300 miles per second (480 km/s), matching the speed of the fast wind.



Observing the region where this wind originates is a true technical feat. The corona, the Sun's atmosphere, is a million times fainter than the solar disk. To study it, astronomers use occulters that block the Sun. But from Earth, these instruments must also hide the part closest to the Sun, where the wind forms. Total solar eclipses offer a natural solution, but they are rare and brief.

The Proba-3 mission overcomes this difficulty with a clever formation-flying technique. Two satellites orbit about 490 feet (150 meters) apart. One acts as an occulter for the other, which observes the corona. Since its launch in December 2024, the duo has performed 57 artificial eclipses, accumulating 250 hours of high-resolution video of the region where the solar wind accelerates.

The results, published in The Astrophysical Journal Letters, show that the slow wind emerges irregularly, creating small-scale magnetic disturbances. According to Andrei Zhukov, a solar physicist at the Royal Observatory of Belgium and lead author of the study, gusts of slow wind in the inner corona—a very difficult region to observe—move three to four times faster than expected. Joe Zander, Proba-3 project scientist at ESA, adds that we can now track the wind's acceleration near the Sun, with surprising speeds.


These first data are just the beginning. Scientists hope to uncover the exact mechanisms behind the generation of the slow wind, which are still poorly understood. Proba-3's ability to produce eclipses on demand opens a new era for space weather forecasting, with implications for predicting geomagnetic storms that can disrupt our satellites and power grids.