Scientists agree that every total solar eclipse is a unique phenomenon, because the halo that appears around the sun changes due to the changing magnetic field, giving each eclipse a completely different shape from the others.
On August 12, 2026, the inhabitants of Greenland, Iceland, Spain and the Balearic Islands (a Spanish archipelago located in the western Mediterranean Sea off the eastern coast of the Iberian Peninsula) will witness a total solar eclipse with a maximum length of only 2 minutes and 18 seconds.
This eclipse will be unique because the shape of the solar corona that appears during it depends on the sun's magnetic activity in the days leading up to the eclipse, as well as the position of sunspots and prominences at that time. Therefore, scientists confirm the impossibility of accurately predicting the corona's appearance beforehand. This uniqueness is what makes the eclipse a precious moment, as it reveals the sun's hidden atmosphere for a fleeting few minutes before it disappears, never to be seen in the same way again.
This eclipse will occur in a downward phase of solar cycle 25, about two years after the peak it reached in October 2024. This means that the corona that will appear will not be as complex as the peak of solar activity, but it will not be as calm as the period of solar calm either, but will fall in an intermediate region.
Although solar cycle 25 peaked in October 2024, solar activity doesn't disappear suddenly, but rather declines gradually. Therefore, the sun is expected to be more active this August than it was during the eclipses of 2017, 2019, and 2020, but less active than it was during the April 2024 eclipse.
Scientists predict that the monthly number of sunspots will be around 102, compared to 144 in the 2024 eclipse, meaning that the corona will be somewhere between simplicity and complexity: not flat and clean as during periods of calm, and not complex and branching as at the peak of activity.
The solar corona is not static; it is a product of extremely hot plasma trapped and shaped by the Sun's magnetic field. During periods of high solar activity, when sunspots are abundant, the corona appears irregular, with sharp, prominent extensions in different directions, as each sunspot region creates its own distinct extension of light. During periods of low solar activity, the corona becomes more regular and smooth, with long bands extending from the sides of the Sun like wings.
Since the 2026 eclipse occurs in the waning phase, the corona is expected to be asymmetrical, with one side being more active than the other, and strong bands extending far into space. Its final shape depends on the position of sunspots near the edge of the sun in the days immediately preceding the eclipse. The sun rotates every 27 days, meaning that any large active region appearing at the edge before the eclipse could drastically alter the landscape. For this reason, the final predictions for the corona's appearance are refined on the day of the eclipse itself.
In addition to the white halo, bright pink or crimson prominences may appear around the edge of the Moon during an eclipse. These are massive structures of hydrogen plasma suspended in the Sun's atmosphere by magnetic fields, glowing brightly in the alpha hydrogen wavelength. These prominences are most visible when the Sun is active and can last for days or weeks, making them easier to predict than solar flares.
The August 2026 eclipse has a favorable geometry for observation. Due to the short duration of the total eclipse (2 minutes and 18 seconds maximum), the moon will be only slightly larger than the sun, which may allow protrusions on both sides of the sun to be seen at the same time, unlike longer eclipses where the moon obscures one side and reveals another in succession.
A coronal mass ejection (CME) is an explosion of plasma and magnetic field from the Sun's atmosphere. While visible during a solar eclipse, it is rare and occurred during the December 2020 solar eclipse. These eruptions take hours to travel through the Sun's atmosphere, so observers will not see any movement during the few minutes of the eclipse, but they may be captured as a still image using long-exposure cameras.
The chances of this occurring increase in active solar environments, making the 2026 eclipse more likely to be observed than eclipses during periods of calm.
Scientists ultimately emphasize that accurately predicting the shape of the corona is impossible, as it depends on the sun's magnetic activity in the days leading up to the eclipse, as well as the position of sunspots and other features at that precise moment. Even if one were to witness another eclipse a month earlier or later, it would be entirely different. This is what makes the eclipse of August 12, 2026, exceptionally significant: the sun's hidden atmosphere will be visible for only a few minutes before disappearing again in the sun's glare, and it will never be repeated in the same way.
