Viewing the Sun's outer atmosphere with the naked eye is an important factor that motivates eclipse observers to travel across the globe. On August 12th, this event has the potential to display a solar corona configuration that will not repeat exactly the same way.
Every total solar eclipse has distinct characteristics. Although the outline of the Moon passing in front of the Sun remains relatively stable, the moment our natural satellite completely obscures the solar disk generates a remarkable spectacle: the appearance of the corona.
The solar corona is considered one of nature's beauties. Observing its fine, pointed white filaments during the brief periods of totality provides a glimpse into infinity, although it is only a fleeting view, since the corona is constantly transforming.
Its formation is determined by the Sun's magnetic field, which is continuously changing, causing it to evolve annually, monthly, and even daily. For this reason, no total solar eclipse presents exactly the same structure.
The Solar Corona and the Solar Cycle
This variability is one of the reasons why eclipse chasers persist in their travels. The corona, which can be observed during the total solar eclipse on Wednesday (12th), if the sky is clear, will serve as a unique record of the Sun at a specific point in Solar Cycle 25. It will reflect years of changes in magnetic activity, thousands of sunspots, and countless emissions of solar material.
After the end of totality, that exact arrangement of the corona will never be seen again. However, is it possible to predict its appearance?
Under normal circumstances, the solar corona—the outer layer of our star—is invisible. It extends millions of kilometers through the Solar System but is obscured by the intense luminosity of the photosphere, which is the visible surface of the Sun.
Totality alters this condition. When the Moon completely covers the photosphere, the corona suddenly appears. White filaments project away from the dark silhouette of the Moon, while pinkish structures and prominences may appear around its edge.
For many novice observers, one of the biggest surprises during totality lies not just in the detail, but also in the dimension. The corona often appears much larger than expected, extending several solar diameters from the eclipsed Sun.
Although photographs can capture part of this complexity, they rarely replicate the perception of depth and structure that the human eye can achieve, given its dynamic range superior to any camera.
The corona is not a static structure; it is composed of extremely hot plasma—ionized and highly energized gas—that remains trapped and shaped by the Sun's magnetic field. Since the solar magnetic field is constantly mutating, the corona also changes.
Magnetic Activity and Corona Structure
Ryan French, a solar physicist, author, and science communicator from the Laboratory for Atmospheric and Space Physics (LASP) located in Boulder, Colorado (USA), and author of 'Little Book of Eclipses: An Essential Companion to Solar and Lunar Events', explained that 'the Sun follows a natural 11-year cycle of increasing and decreasing activity.'
He added that 'at the peak of this cycle, known as solar maximum, there are many sunspots on the Sun, which are giant magnets installed at the base of the solar atmosphere. These sunspots generate many solar flares and coronal mass ejections, which are a kind of explosions and energy irradiations from the Sun's atmosphere. During solar minimum, the Sun shows none of this.'
This magnetic activity defines the general shape of the corona. During solar minimum, when the Sun has few or no sunspots, the corona tends to look more symmetrical and uniform. Long filaments often extend from both sides of the Sun, giving the corona a wing-like appearance.
In contrast, during solar maximum, the structure can be considerably more elaborate. Sunspot areas act as magnetic anchor points, creating shapes that can resemble spikes or filaments projecting in various directions.
French commented: 'If you observed a total eclipse during solar maximum, the solar corona would look almost like a cartoon star with five points.' He justified this by saying that each of these sunspot regions generates a spiral or point that can be seen with the naked eye.
Predictions and Conditions for the August Eclipse
Current projections for August 2026 indicate a number closer to 102 sunspots. Although significantly fewer, the activity is still classified as high compared to recent cycle patterns.
This suggests that observers should expect something intermediate between the two extremes: neither a smooth, flattened corona typical of solar minimum, nor the most intense spectacle of solar maximum.
A useful analogy can be made with total solar eclipses that occurred near the previous solar maximum. Solar Cycle 24, which peaked in April 2014, was relatively weak. The total eclipses closest to that peak included the unusual hybrid eclipse of November 3, 2013, when the monthly number of sunspots hovered around 113.
Solar Cycle 23, which had two peaks—in March 2000 and November 2001—was more vigorous. The closest total solar eclipse occurred on June 21, 2001, when the monthly number of sunspots was around 203. Its corona was likely more complex than what is expected for 2026.
Therefore, the 2026 eclipse falls into an intermediate category. It will not be a repeat of the 2024 eclipse, nor will it be an eclipse under a calm Sun.
During the declining phase of an active cycle, the corona should present robust filaments that extend over large distances in space, but with greater asymmetry, with one side being more dynamic than the other.
French stated: 'It is specifically the sunspots near the edge of the Sun that determine how the corona will look.'
The Sun completes one rotation every 27 days. Consequently, any large active area of sunspots appearing on the edge of the Sun shortly before August 12th could drastically alter the appearance of the corona.
For this reason, any predictions about its appearance—usually released by Predictive Science about a week before the eclipse—tend to be adjusted on the day of the phenomenon itself.
Visible Structures During Totality
One of the most impactful sights during totality is the appearance of intensely pink or reddish structures around the edge of the Moon. Generally, these structures are prominences—vast formations of hydrogen plasma suspended above the solar surface by magnetic fields. Beginners often confuse these prominences with solar flares, as happened after the total solar eclipse of 2024.
French clarified: 'Prominences are large magnetic structures that suspend plasma in the Sun's atmosphere and shine intensely at a very specific wavelength of light called hydrogen-alpha.'
Prominences are more frequent when the Sun is active. Since they can last for days or weeks, they are also easier to anticipate than a solar flare.
In hydrogen-alpha images taken before the eclipse day, observers will be able to identify which prominences are present around the edge of the Sun.
The 2026 eclipse may provide favorable conditions for observing these structures. This is because the Moon will appear only slightly larger than the Sun, a characteristic that also contributes to the relatively short duration of totality, of a maximum of two minutes and 18 seconds. Thus, smaller prominences on different sides of the Sun may be visible simultaneously.
The situation differs in longer eclipses, where the seemingly larger Moon may hide prominences on one side before revealing others on the opposite side.
A coronal mass ejection, abbreviated as CME, is an expulsion of plasma and magnetic field originating from the solar atmosphere. Observing such a structure during totality is possible—this happened during the total solar eclipse of December 14, 2020—but requires great luck.
French explained: 'CMEs travel very slowly, so it takes several hours to cross and escape the Sun's atmosphere. Therefore, you would not see any movement during an eclipse.'
He added: 'But what you might see, if you are lucky, would be an instantaneous photograph of a flare—although a long-exposure camera is probably more likely to record it than your eyes.'
Such a sight would be rare, but the chances increase when the Sun is in an environment of higher activity, compared to periods close to solar minimum.
Predictive Science will issue a forecast regarding the appearance of the solar corona. The model may be so accurate that some eclipse chasers choose not to consult it to preserve the surprise of totality.
One way to get a general idea is to follow real-time images generated by telescopes using coronagraphs to block sunlight, such as the COSMO K-Coronagraph, LASCO C3 from the NASA's SOHO mission, and GOES CCOR-1.
To monitor sunspots, it is also possible to consult the latest H-alpha image produced by the Global Oscillation Network Group (GONG). No scientist, however, can determine exactly how the corona will look on August 12th.
This will depend on the Sun's magnetic activity in the days immediately preceding totality, the position of sunspot clusters, the presence of prominences, and the possibility of eruptions.
French concluded: 'Exactly what we will see during the August eclipse will depend on the activity that week.' He emphasized: 'And even if you saw an eclipse a month before or a month after, it could be very different.'
For a few fleeting minutes over Iceland, Spain, and the Balearic Islands, the hidden atmosphere of the Sun will become momentarily visible before returning to the star's brilliance.
And that specific configuration of the corona, recorded during the August 12th eclipse, will never be seen exactly the same way.
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