A pair of satellites launched by the European Space Agency (ESA) will create artificial solar eclipses to study the sun’s enigmatic corona, offering unprecedented insights into one of the most fascinating phenomena in astronomy.
At a glance:
- The Proba-3 mission uses two satellites to create artificial eclipses, allowing extended observation of the sun’s corona.
- The corona, the sun’s outer atmosphere, is hotter than the sun’s surface, reaching up to 2 million degrees Fahrenheit.
- Proba-3’s innovative two-satellite design offers higher precision and less light interference than previous single-satellite coronagraph missions.
- First results from the mission are expected in early 2025.
Launched earlier this month from India, the ESA’s Proba-3 mission marks a groundbreaking approach to solar observation. Using two satellites flying in precise formation, the mission aims to simulate solar eclipses to study the sun’s corona, its mysterious and superheated outer atmosphere.
The mission’s innovative design includes one satellite (the Occulter) casting a shadow over the second satellite (the Coronagraph), which captures detailed images of the corona. This setup allows astronomers to bypass the limitations of Earth-based solar eclipses, which are rare and fleeting.
“The ability of this mission to observe the corona so close to the sun for extended periods is an extraordinary opportunity,” said Talwinder Singh, Assistant Professor of Physics and Astronomy at Georgia State University. “If successful, it will pave the way for similar missions that provide continuous, high-resolution observations of the sun’s corona.”
Why study the corona?
The corona presents one of the sun’s greatest mysteries: it is significantly hotter than the sun’s surface. While the sun’s surface reaches temperatures of about 10,000 degrees Fahrenheit, the corona can exceed 2 million degrees.
Observing the corona is extremely challenging because it is hidden by the bright light of the sun’s surface. Total solar eclipses, which naturally reveal the corona, are rare and brief. The next one will not occur until August 2026.
Proba-3’s two-satellite design overcomes these limitations. “The occulter is actually on a different spacecraft, so it can be quite far away,” said Kathy Reeves, Senior Astrophysicist at the Center for Astrophysics at Harvard & Smithsonian. “Using this technique, the instrument can block the sun’s disk more precisely.”
A technological breakthrough
Previous missions used single-satellite coronagraphs to create artificial eclipses, but this design often led to light interference, restricting how close scientists could observe the sun.
Proba-3’s two satellites fly about 500 feet apart, enabling high-precision alignment and reducing light scattering. This allows scientists to observe the corona’s middle layers, an area previously difficult to study.
The mission will provide extended observation periods, with up to six hours of continuous eclipse-like conditions during each 20-hour orbit. This is a significant improvement over natural eclipses, which last only minutes.
“Natural eclipses only happen once or twice per year, sometimes in inconvenient places, like over the ocean,” Reeves explained. “This mission is really neat because it will extend the amount of time scientists can study the sun’s middle corona from minutes to hours.”
Looking ahead
Proba-3 will begin its detailed observations in early 2025, with the first scientific results expected around four months later. While the artificial eclipses will not impact Earth, the mission is expected to advance our understanding of the sun’s corona and its effects on space weather, which can disrupt satellite communications and power grids.
By revolutionizing solar observation, Proba-3 could set a precedent for future missions to unlock the mysteries of our closest star.
