On 17 February 2026, the Sun–Moon–Earth system aligned to a precise geometric configuration that produced an annular solar eclipse. During this configuration, the apparent angular diameter of the Moon was slightly smaller than that of the Sun. As a result, the lunar disk could not fully occult the photosphere. Instead, a narrow ring of solar emission remained visible.

While the event was largely inaccessible to ground observers due to its Antarctic track, the European Space Agency’s Proba-2 spacecraft observed the eclipse under stable orbital conditions. Its extreme ultraviolet measurements now provide a scientifically valuable record of the event.

The geometry behind the February 2026 eclipse

A solar eclipse always depends on exact orbital geometry. The Moon must pass directly between Earth and the Sun. However, the visual outcome changes depending on the Moon’s distance from Earth. Because the lunar orbit is elliptical, the Moon’s apparent size varies by several percent over the course of a month.

During the February 2026 event, the Moon was positioned near apogee. Consequently, its angular diameter fell short of the Sun’s apparent size. This mismatch produced an annular eclipse rather than a total one. Observers located along the central path would have seen a bright ring of sunlight surrounding the Moon’s silhouette.

The peak annular phase occurred near 11:31 UTC. At maximum, the Moon covered roughly 96 percent of the solar diameter. Although this level of coverage is substantial, it still leaves enough photospheric light to prevent totality. Therefore, the solar corona did not become visible in white light from the ground.

Limited Visibility from Earth

Despite the scientific interest, this eclipse offered poor viewing conditions for most of the world. The path of annularity crossed the Southern Ocean and Antarctica. Only a small number of research stations lie within the narrow zone of maximum alignment.

Outside this path, some regions in the Southern Hemisphere experienced a partial eclipse. However, large populated areas across Asia, Europe, and most of Africa saw nothing at all.

Even within Antarctica, weather and logistics posed challenges. Polar conditions often limit ground-based observations. Cloud cover, extreme cold, and limited accessibility reduce the chances of successful imaging. For these reasons, space-based observations became especially important for documenting the event.

Proba-2 and its solar monitoring role

ESA launched Proba-2 in November 2009 to support solar research and technology demonstration. Although compact in size, the spacecraft carries a capable suite of instruments. Among them, the SWAP imager plays a central role in monitoring the Sun’s outer atmosphere.

SWAP operates at a wavelength of approximately 17.4 nanometres in the extreme ultraviolet range. This spectral region reveals plasma structures in the solar corona that remain invisible in ordinary light. Because the corona reaches temperatures exceeding one million degrees Celsius, it emits strongly in EUV wavelengths.

The spacecraft follows a sun-synchronous low-Earth orbit. This orbital configuration keeps the satellite in consistent lighting conditions while allowing frequent solar observations. Importantly, during the February 2026 eclipse, the orbit caused Proba-2 to intersect the Moon’s shadow multiple times. ESA reported four separate eclipse observations during successive passes.

This repeated sampling provided an unusually rich dataset. Instead of a single moment of alignment, scientists obtained several views under slightly different geometries. Such coverage improves both calibration and scientific interpretation.

The eclipse as seen in extreme ultraviolet

The Proba-2 images differ markedly from familiar eclipse photographs. In visible light, annular eclipses display a bright orange or white ring. In contrast, SWAP records the Sun’s EUV emission. Therefore, the released imagery emphasizes the hot coronal plasma rather than the photosphere.

In the processed frames, the Moon appears as a sharply defined dark disk. Surrounding it, the solar atmosphere glows in structured patterns. Magnetic loops and extended coronal regions become visible with high contrast. Because the observations occur above Earth’s atmosphere, the limb definition remains exceptionally clean.

Each orbital pass shows subtle changes in alignment. In some frames, the Moon sits slightly off-center relative to the Sun. In others, the annular ring appears more symmetric. These variations arise from the spacecraft’s motion combined with the evolving Sun–Moon geometry.

From a technical standpoint, such occultation events are useful. When the Moon blocks part of the Sun, it creates a natural calibration edge. Scientists can analyze how the instrument responds to sharp intensity transitions. This helps refine image processing and radiometric accuracy.

Importance of space-based eclipse data

Observing eclipses from orbit offers several advantages. First, spacecraft avoid atmospheric turbulence. Ground-based solar imaging always suffers from seeing effects, even at excellent sites. In orbit, the optical path remains stable.

Second, satellites can observe continuously. They do not depend on local daylight or weather conditions. This allows multiple measurements during a single eclipse event. In the February 2026 case, Proba-2 captured four separate sequences.

Third, extreme ultraviolet imaging reveals physical processes that visible light cannot show. The photosphere dominates white-light observations. However, EUV data highlight the corona and transition region. These layers play a major role in solar activity and space weather.

Understanding coronal structure remains a key objective in solar physics. Magnetic fields shape the corona into loops and arcades. These structures store and release energy through flares and coronal mass ejections. By examining EUV brightness patterns during occultations, researchers can test models of plasma distribution and magnetic topology.

Clear skies!

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