Topline
If you were lucky enough to witness last week’s total solar eclipse, you’ll have seen one of nature’s rarest spectacles — the sun’s wispy white corona glowing around a silhouette of the moon. It’s a view that has helped transform solar science for generations, including proving Albert Einstein right. Now scientists no longer have to wait for the moon to provide that opportunity. By flying two spacecraft in extraordinarily precise formation, the European Space Agency’s Proba-3 mission is creating artificial solar eclipses lasting up to five hours at a time, offering an unprecedented view of the corona — with early results revealing new information about the solar wind.
Key Facts
Normally, the only opportunity to study the sun’s faint corona comes during a total solar eclipse, when the moon blocks the brilliant solar disk. Those events occur somewhere on Earth only about every 16 months and totality rarely lasts longer than a few minutes.
Launched in December 2024, Proba-3 consists of two separate spacecraft that fly in formation with extraordinary precision, maintaining their relative positions to within just a few millimeters over distances of 472 feet (144 meters. Together they function as a single giant coronagraph, with one spacecraft carrying an occulting disk that blocks the sun while the other observes the faint corona with a telescope.
Unlike a natural total solar eclipse, which typically lasts only a few minutes at any one location on Earth, Proba-3 can create artificial eclipses lasting up to six hours per orbit. That allows scientists to study subtle changes in the solar corona for much longer periods than during a brief natural solar eclipse.
In February 2026, engineers temporarily lost contact with Proba-3 following a software anomaly. After weeks of recovery efforts, the spacecraft was successfully revived, its software patched and formation flying resumed.
The Solar Wind And The Sun’s Corona
The solar wind constantly streams away from the sun, carrying charged particles throughout the solar system and causing geomagnetic storms capable of disrupting satellites, radio communications, navigation systems and even electricity grids on Earth. Understanding how the solar wind forms and accelerates is one of the biggest unanswered questions in solar physics. Proba-3’s main scientific target is the source of the solar wind — the solar corona, the sun’s superheated outer atmosphere, which reaches temperatures of more than a million degrees Celsius. That’s despite the sun’s visible surface — its photosphere — being much cooler. NASA has spacecraft (SOHO’s LASCO, Solar Orbiter’s Metis and GOES CCOR-1) that study the corona using occulting disks, but Proba-3 can look much closer to the sun — about 44,000 miles (70,000 kilometers) above the sun’s surface, an area that has remained largely hidden from previous space telescopes. This inner corona is already giving up its secrets to Proba-3.
The Solar Wind Is Faster Than Expected
The mission’s first scientific results have already surprised researchers since its first artificial solar eclipse in orbit. By tracking tiny blobs of plasma moving through the inner corona, scientists found that parts of the so-called slow solar wind are traveling between 250 and 500 kilometers per second — three to four times faster than previous models predicted so close to the sun. “In the inner corona, a region very difficult to observe, we saw slow solar wind gusts moving three to four times faster than expected,” said Andrei Zhukov of the Royal Observatory of Belgium, the principal investigator of Proba-3’s ASPIICS instrument and the lead author of a study published in March. Researchers also observed intricate flows, jets and streamers moving through the corona in remarkable detail.
Total solar eclipses have driven major scientific breakthroughs for more than a century, most famously providing one of the first observational tests of Einstein’s general theory of relativity in 1919.