The Sun’s corona, its outer atmosphere, is typically only visible during natural total solar eclipses that occur roughly every 18 months along a narrow path on Earth. However, the recent Proba-3 mission by the European Space Agency (ESA) has changed the game for solar scientists by creating the world’s first artificial total solar eclipse.

The Proba-3 mission consists of two satellites, the Occulter and the Coronagraph, which autonomously aligned in space to block out the Sun’s surface and capture images of the corona. This breakthrough not only expands access to solar data but also showcases a new level of satellite formation flying.

Andrei Zhukov, principal investigator for the Association of Spacecraft for Polarimetry and Imaging Investigation of the Corona of the Sun (ASPIICS) at the Royal Observatory of Belgium, expressed his excitement over the success of the mission, stating that the images were obtained on the first try.

The Proba-3 mission was launched on December 5, 2024, with the Occulter and Coronagraph sent to solar orbit. In May, the two satellites achieved a remarkable feat by autonomously aligning in space with millimeter precision and maintaining their relative position for hours without ground control intervention.

To create the artificial eclipse, the satellites had to align with a specific distance between them, allowing the Occulter to cast a shadow on the Coronagraph's optical instrument. This shadow effectively blocked out the Sun's surface, enabling the Coronagraph to capture images of the corona.

According to Zhukov, the artificial eclipse images are comparable to those taken during a natural eclipse, but with the advantage of being able to create the eclipse once every 19.6-hour orbit. This is in contrast to natural total eclipses that occur very rarely and last only a few minutes.

The data collected from this mission will provide valuable insights into the Sun's corona, which is essential for understanding solar wind, coronal mass ejections, and solar weather that can impact Earth's satellites, communication systems, and power grids.

Furthermore, the Proba-3 mission aims to address the coronal heating problem, a scientific mystery where the Sun's corona reaches temperatures significantly hotter than its surface. By studying the corona up close, the mission hopes to provide answers to this long-standing question in solar physics.

Overall, the success of the Proba-3 mission not only advances solar science but also lays the groundwork for future multi-spacecraft missions, such as ESA's Laser Interferometer Space Antenna (LISA), by demonstrating autonomous precision formation flying.

Proba-3 will continue to observe the Sun's corona for about two years, providing scientists with a wealth of new data to enhance their understanding of our life-sustaining star.