A Double Eclipse for Proba-3
On 12 August 2026, parts of Europe experienced a total solar eclipse as the Moon's shadow swept across Greenland, Iceland, and northern Spain. But hours before the natural eclipse reached European shores, the European Space Agency's Proba-3 mission had already created its own eclipse from orbit—producing the mission's most detailed images yet of the Sun's inner corona.
Proba-3 is a precision formation-flying mission consisting of two spacecraft: an Occulter spacecraft and a Coronagraph spacecraft. By maintaining a separation of approximately 150 metres between the two, the Occulter casts a shadow on the Coronagraph's ASPIICS telescope, creating an artificial eclipse that can last for hours—far longer than the few minutes of totality offered by a natural eclipse.
The Mission
Proba-3 was launched in December 2024 and is the first mission dedicated to demonstrating precision formation flying at such close range. The mission's primary scientific instrument is ASPIICS (Association of Spacecraft for Polarimetry and Imaging Investigation of the Corona of the Sun), a coronagraph that observes the solar corona—the Sun's outer atmosphere—in visible light.
Studying the corona is notoriously difficult because it is roughly a million times fainter than the solar surface. From the ground, it can only be seen during the brief minutes of a total solar eclipse. Space-based coronagraphs exist, but they suffer from diffraction effects caused by the close proximity of the occulting disk to the telescope. Proba-3 overcomes this by placing the occulter 150 metres away from the telescope, dramatically reducing diffraction and producing sharper, more detailed images.
The mission experienced operational anomalies early in 2026 but successfully resumed its scientific observations in July 2026, just in time for the August eclipse season.
The 12 August 2026 Observations
On 12 August 2026, Proba-3 performed a specially planned observation sequence timed to coincide with the natural total solar eclipse that crossed Europe later that day. The spacecraft created its artificial eclipse hours before the Moon's shadow reached Earth, producing coronal images that complemented ground-based eclipse observations.
The Sun's inner corona appeared greenish in the ASPIICS images, revealing fine structures that are typically obscured by the bright solar disk. These structures—including streamers, plumes, and coronal loops—hold clues to the mechanisms that heat the corona to millions of degrees and accelerate the solar wind.
By combining Proba-3's sustained observations with the brief but high-resolution ground-based images from the natural eclipse, solar physicists gained an unprecedented dataset. Proba-3 provided the temporal context—how the corona evolves over hours—while the natural eclipse provided a snapshot from a different viewing geometry.
The Natural Eclipse of 12 August 2026
The total solar eclipse of 12 August 2026 was the first total eclipse visible in Europe since 1999. The path of totality crossed Greenland, Iceland, the Atlantic Ocean, and northern Spain before ending at sunset in the Mediterranean. A partial eclipse was visible across much of Europe, North America, and northern Asia.
In Spain, the eclipse occurred at sunset, creating a dramatic spectacle as the Sun set while partially or totally eclipsed. Cities in the path of totality, including León and Oviedo, drew large crowds of eclipse watchers. The eclipse was also notable for its duration: totality lasted a maximum of 2 minutes and 18 seconds on the centre line.
NASA provided detailed predictions and safety guidance for the event, emphasising the importance of using certified solar filters for direct viewing. The agency also coordinated with researchers across the path of totality to collect scientific data during the brief window of darkness.
Formation Flying: An Engineering Feat
The technical challenge of Proba-3's formation flying cannot be overstated. The two spacecraft must maintain their relative position to within a few millimetres while orbiting Earth at approximately 7 km per second. This requires a sophisticated guidance, navigation, and control system that uses metrology sensors, micro-thrusters, and autonomous decision-making algorithms.
If the formation breaks, the artificial eclipse is lost. If the spacecraft drift too close, there is a collision risk. The mission's success in maintaining formation over extended periods demonstrates a capability that has applications beyond solar science—including future space-based interferometers, distributed satellite systems, and in-orbit servicing missions.
Looking Ahead
The 12 August 2026 eclipse was a milestone for Proba-3, but the mission's scientific programme continues. Over its operational lifetime, Proba-3 will observe the corona through different phases of the solar cycle, which is currently approaching its maximum in 2025–2026. Solar maximum is characterised by increased sunspot activity, more frequent coronal mass ejections, and a more complex corona—ideal conditions for Proba-3's instruments.
The mission's data will be made available to the scientific community through ESA's archives, supporting studies of coronal heating, solar wind acceleration, and space weather prediction. As the Sun's activity evolves over the coming years, Proba-3's sustained coronal observations will provide a unique record of how the solar atmosphere responds to the changing magnetic cycle.
Sources
- ESA, Proba-3's first artificial solar eclipse, esa.int/Enabling_Support/Space_Engineering_Technology/Proba-3_s_first_artificial_solar_eclipse
- ESA, Proba-3's eclipse hours before totality in Europe, esa.int/ESA_Multimedia/Images/2026/08/Proba-3_s_eclipse_hours_before_totality_in_Europe
- ESA, A double eclipse for Proba-3, esa.int/ESA_Multimedia/Videos/2026/08/A_double_eclipse_for_Proba-3
- Daily Galaxy, ESA's Proba-3 Created Its Own Solar Eclipse Just Hours Before the Real One, dailygalaxy.com, August 2026
- NASA, Total Solar Eclipse on August 12, 2026, science.nasa.gov/eclipses
- COSMOS, Proba-3, cosmos.esa.int/web/proba-3
FIRAT Editorial Board
Institutional Research Desk · Foresight Institute of Research and Translation
The collective editorial and research translation board of FIRAT, synthesising peer-reviewed evidence, policy briefs, and division milestones across our seven foundational research pillars.
