Scientists create stunning models of how sun will look during eclipse

The corona is the outermost part of the sun’s atmosphere, which Earth-dwellers can only see during total solar eclipses. Its appearance constantly evolves because of the sun’s ever-changing magnetic field and is different during every solar eclipse. But, on April 8, it will be particularly stunning, according to a newly released simulation from Predictive Science, a San Francisco-based company that develops computer models of the sun and whose work supports a number of NASA missions.

The simulation reveals a dramatic starburst-like pattern with numerous large prominences, including at 7 o’clock bearing, 10 o’clock and 2 o’clock. Nearer to the solar disk, a few looping features are visible as well.

Predictive Science has a history of making successful eclipse predictions. But this eclipse will be harder to forecast than normal. That’s because the current 11-year solar cycle is near its peak or maximum, when the sun’s magnetic field is most chaotic.

The behavior of this magnetic field is important because it contorts the plasma, or the glowing superheated gas that makes up the corona. This luminous plasma traces the sun’s magnetic field.

“Magnetic flux on the sun near solar maximum changes a lot,” Jon Linker, president of Predictive Science, said in an interview. “Previously we could do a month in advance [prediction] and then another prediction a week in advance. But right now the sun is very dynamic, which makes it very challenging. We’re doing something more ambitious this year, in that it’s a time-evolving model.”

Despite the challenges in forecasting, Bob Leamon, a NASA researcher focused on solar physics, said that he expects this to be the most spectacular corona of a lifetime.

During eclipses, the corona tends to be least interesting during a solar minimum, when the sun may be without sunspots for days or weeks. Sunspots are regions of enhanced magnetism on the sun; a lack of sunspots means an unremarkable magnetic field, and a rather simple corona. At the sun’s north and south poles, “polar streamers” of plasma follow magnetic field lines out of or into the sun, but there aren’t many loops, prominences or noteworthy features.

That was the case in 2019 during a total eclipse in Chile:

But with solar maximum slated for sometime in mid-2024, scientists anticipate the most dynamic corona possible.

“The more solar activity, the more spikes all the way around from the sun,” Leamon said. “I think it’s going to be really cool.”

On April 20 last year, a brief total solar eclipse gave 1 minute 2 seconds of totality to areas near Learmonth on the extreme northwest cape of Australia. Notice how much more dynamic the corona was compared with the eclipse in 2019:

There are even more reasons the corona on April 8 has the potential to be quite special. Two major sunspot clusters could contort the corona into even more spectacular shapes.

Of particular interest is the reincarnation of AR3590 (AR stands for active region), a sunspot cluster that produced a trio of top-tier X-class flares in late February. It could rotate from the sun’s far side back into view, which could produce prominences, or large streamers and loops of magnetism.

Beyond prominences, there’s a chance we may catch a glimpse of a dramatic solar phenomenon known as a coronal mass ejection or CME. That’s an eruptive burst of plasma and magnetism from a sunspot. CMEs can interact with Earth’s magnetic field and lead to auroras for our viewing pleasure (but they usually take at least a day or two before bombarding our magnetic field).

“With flares and eruptions, there’s a very real possibility that we can see a CME going off the side of the sun,” Leamon said. “That would be absolutely awesome.”

During the eclipse, ground viewers would see only a phase of a CME in the course of a few minutes, such as some material detaching from the sun. The entire eruption would span an hour or more, which could be observed by stitching many images together taken by people or scientific instruments across the path of totality.

“You might see a large bubble coming off the sun,” Linker said. “I think even in the last couple eclipses, there were small CMEs, and there are drawings in the past where people would sketch this bubble.” Some of those drawings date back to the 1870s.

If one launches right before totality, he’s hoping his time-evolving model will capture it and predict its behavior — and what it will look like.

Predictive Science is planning to continuously update its predictions of the corona as more data becomes available leading up to the eclipse. They can be accessed here.