A total solar eclipse has always been a rare and awe-inspiring event, both for casual skywatchers and scientists alike. But now, we no longer have to wait for this infrequent natural phenomenon.
Thanks to the European Space Agency’s (ESA) Proba-3 space mission, we can now witness an “artificial solar eclipse” from Earth’s orbit—on demand, every 20 hours!
Two Satellites, One Grand Mission
Launched on December 5, 2024, from India, Proba-3 has already successfully created nine artificial eclipses during its trial phase. Over the next two years, it is expected to generate more than 1,000 hours of eclipse observations.
Proba-3 consists of two satellites that move together like a pair of celestial dancers. The first satellite, known as the Occulter, blocks sunlight. The second, called the Coronagraph, trails closely behind to capture images of the Sun’s corona—the intensely hot outer layer of the solar atmosphere.
These two satellites fly in extremely precise formation, separated by about 150 meters and aligned with millimeter-level accuracy. Advanced positioning and navigation systems—including GPS, star trackers, and laser sensors—allow them to move in perfect sync, almost as if they were a single spacecraft.
Why Artificial?
Natural total solar eclipses occur only once or twice a year, and can only be seen from a narrow strip of Earth's surface, typically lasting just a few minutes.
With Proba-3, ESA can generate an eclipse every 19.6 hours, each lasting up to six full hours! This provides scientists with far more time to study the Sun’s corona in detail—something previously impossible with fleeting natural eclipses.
Unveiling the Mysteries of the Solar Corona
The Sun’s corona remains one of its most mysterious regions. Its temperature can exceed one million degrees Celsius—nearly 200 times hotter than the Sun’s surface. Why it gets so incredibly hot is still unknown, and this is where Proba-3 plays a crucial role.
Equipped with the ASPIICS instrument (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun), the Coronagraph can capture images of the corona without interference from the Sun’s direct light. More than that, it can also detect light across multiple wavelengths, including emissions from superheated elements like ionized iron.
Thanks to its ultra-clean, low-scatter images, Proba-3’s visual data far surpass the capabilities of traditional ground-based coronagraphs. According to scientist Andrei Zhukov from the Royal Observatory of Belgium, these images rival even the best natural solar eclipse photographs ever taken.
More Than Just Stunning Images
Beyond ASPIICS, the mission also carries two other instruments: DARA (Digital Absolute Radiometer), which measures the Sun’s total energy output in real-time, and 3DEES (3D Energetic Electron Spectrometer), which monitors high-energy electrons within Earth’s radiation belts.
Data from Proba-3 are essential for understanding phenomena such as the solar wind and coronal mass ejections (CMEs)—two processes that have major effects on space weather. While CMEs can create spectacular auroras, they also have the potential to disrupt satellites, communication networks, and power systems on Earth, as seen during the major disturbance in May 2024.
The Future of Digital Eclipses
Even more exciting, data from Proba-3 are already being used to create digital eclipse simulations. Models like COCONUT, developed by KU Leuven, are now being enhanced using real data from this mission.
This allows scientists to predict and analyze the Sun’s behavior with greater precision—opening up new possibilities for understanding how solar activity can directly affect life on Earth.
