Two satellites successfully produced artificial solar eclipses to investigate the Sun’s enigmatic outer atmosphere, and today the European Space Agency unveiled the first photographs from its Proba-3 mission, marking a significant milestone in space exploration.
The photos show the Sun’s corona, or the blazing halo of plasma that surrounds our star, not during a natural eclipse but rather one that was created by spacecraft that were positioned precisely 150 meters apart. This accomplishment opens up new avenues for solar research as it is the first time that humans have produced long-lasting artificial solar eclipses in space.
The Impossible Becomes Commonplace With Precision Engineering
In order for Proba-3 to function, two satellites that were launched in December 2024 must perform a meticulously planned dance. The Coronagraph Spacecraft trails after with a telescope aimed at the man-made shadow, while the Occulter Spacecraft holds a 1.4-meter disk that places itself squarely in front of the Sun.
“By lining up with the Sun, one spacecraft will cast a precisely controlled shadow onto another, to cover the Sun’s brilliant disk entirely, so that the million-times-fainter solar corona will become visible for sustained observation,” stated Damien Galano, mission manager for Proba-3.
Star trackers, cameras, lasers, and thrusters are needed to maintain the formation’s millimeter-scale accuracy on its own. In contrast to natural eclipses, which only last a few minutes, this enables the artificial eclipse to endure up to six hours throughout each 19.6-hour orbit.
Solving The Mysteries Of The Sun
The “coronal heating problem”—why the Sun’s surface barely reaches 10,000 degrees Fahrenheit while its corona reaches 2 million—is one of the core questions the mission attempts to answer regarding solar physics.
“Our ‘artificial eclipse’ images are comparable with those taken during a natural eclipse,” stated Andrei Zhukov, Principal Investigator for the primary instrument of the project. “The difference is that we can create our eclipse once every 19.6-hour orbit, while total solar eclipses only occur naturally around once, very rarely twice a year” .
The initial photographs show several characteristics of the corona, such as solar prominences, which are big loops of plasma arcing from the Sun’s surface, and ionized iron, which indicates the hottest areas. Scientists anticipate that these observations may shed light on solar eruptions known as coronal mass ejections, which have the potential to interfere with satellites and Earth’s electrical systems.
The mission is still under commissioning after it achieved precision formation flying in May 2025. Future space missions involving numerous coordinated spacecraft may be made possible by the success, which showcases formation flying capabilities.
“I was absolutely thrilled to see the images, especially since we got them on the first try,” Zhukov stated.
Technology For Formation Flying
In addition to being a scientific mission, Proba-3 is a technical showcase. It mainly demonstrates previously unheard-of precision formation flying techniques as part of ESA’s Project for On-Board Autonomy series, with two spacecraft maintaining positions with millimetric accuracy while 150 meters apart. The scientific goal of the mission—to create fake solar eclipses to study the Sun’s corona closer to the solar rim than previously allowed—is made achievable by this technological achievement.
The DARA (Digital Absolute RAdiometer) is used to measure Total Solar Irradiance, while the ASPIICS coronagraph is used to image the corona. Electron spectra in Earth’s radiation belts will also be measured by the 3D Energetic Electron Spectrometer (3DEES). The spacecraft duo can sustain formation for up to six hours per 19.7-hour orbit by flying in a highly elliptical orbit with an apogee of 60,500 km, potentially producing up to 50 artificial eclipses per year. This ground-breaking method enables long-term monitoring of the dynamics and structure of the corona, aiding researchers in their understanding of how solar eruptions and coronal heating processes impact space weather.