Solar Chromosphere and Corona Revealed in a Unique Image Captured During Total Solar Eclipse 2024

The Idea

Since I started in solar photography, I imagined how incredible it would be if we could capture both the solar chromosphere and the beautiful solar Corona, knowing that at first sight it seems to be an impossible task, indeed I thought it could be possible, not in a single capture, of course, but with special techniques and during the unique occasion of a total solar eclipse. So the opportunity came up on 8th April 2024 with the Total Solar Eclipse 2024 visible across US. I already had planned to capture an HDR image in white light of the Solar Corona from Texas, so I challenged my friend James Sinclair to capture at the same time a few images of the solar chromosphere immediately before the eclipse starts (C1) and immediately after ending, to avoid the presence of the moon while covering the sun. So my idea was being able to produce a real image – as much as accurate as possible – of the solar chromosphere with its filaments, active regions and prominences aligned along with its corresponding loops and streamers of the solar corona captured and visible at approximately the same time. We knew that this was a huge challenge with so many factors that could go wrong, but fortunately everything went well and we finally could produce a charming unique image, probably never seen before.

Making an high resolution HDR image like that represents an enormous amount of personal and professional efforts, as well as an incredible financial investment, and everything started many months before the Eclipse itself happened. To read to full story, please read the article of my Sun’s Aura, featuring the original HDR image in white light.

Technical processing and Color

After processing my HDR image of the Sun’s Corona (extensive article about it), I then processed the solar disc in Ha captured by James Sinclair from Southern Utah, with a Lunt LS130 and a camera Apollo M Max from Player One Astronomy, as result of a stack of 200 best frames for the single disc image. I used the inversion techinque with curves to better display the details of the sun’s chromosphere. The colors of the solar corona, are showed in orange/brown hues to match with the solar chromosphere for an aesthetic pleasent transition. Important to mention though that corona is not possible to see in Ha emission as we see the solar chromosphere through an Ha filter. The corona was captured in white light through our earth atmosphere which scattered the light giving a bluish appearance during Totality. But the sun corona in space should look like white light, as well as our Sun star.

The Sun’s Corona

The Corona is extremely hot and dynamic, being the outermost layer of the Sun’s atmosphere, it reveals intricate fine structures of delicate details distorted by the strong magnetic fields. Specially, close to the Solar maximum expected for 2025 (peak of 11 years cycle of activity), the plasma of the Sun’s corona features a lot of loops and wispy white streamers radiating into space. But due to an immense level of brightness it is only possible to see when the Moon is perfectly covering the Sun. Safe enough to enjoy with our naked-eyes, much more well prepared and efficient to comprise and accommodate a larger high dynamic range, than our cameras, which even nowadays can’t do it at once. This is why we need to cover around 14 stops in the dynamic range and probably even more would be best, but bracketing can help achieve this milestone.

And why this image is so special ? Because not even SOHO in space, from NASA, can watch the inner corona of the Sun. It only can see the most extensive part of the outer corona, using a coronagraph, from two solar radii distant of the Sun’s centre.

Why Eclipse HDR is so Challenging

Photographing a Total Solar Eclipse, is probably to most advanced and complex task in all of astrophotography fields, not only from preparing and planning which requires a bit of Math to find the correct set of exposures according to your gear combination, ISO, lens aperture, right place to be, right time to start etc, etc, as well as from executing it in a stressful short amount of time. But also very hard and difficult to process in a time consuming task. First, because the Sun, the Moon and the stars have all different motions across the sky, which are evident in long focal distances and long exposures. Images must be aligned not on the Moon’s disc, not on the stars, and not even on the prominences (as it only works in shorter exposures), so to reveal the corona in full glory, images must be aligned on the coronal structures which are very hard and tricky, as they are faint, subtle and lacking of contrast, and they keep moving too on a lower speed. Noticeable though over the course of all bracketing, but inevitably negligible, for the final fusion in order to naturally reduce the presence of noise. And probably the most difficult final achievement, is to keep as much as possible, everything looking natural without overcooking it. It is a delicate balance between, contrast, light flow, color and detail which I tried to keep in mind and respect until the very end. I hope I did it!

Equipment and Exposures for Corona

The High Resolution image was captured with a Sigma lens at 600mm at f6.3, and a Nikon D850 modified (Ha sensitive – not relevant for this type of TSE images) on a Vixen portable mount. I did more than 163 photos (bracketed exposures), but I’ve only selected 72 images (8 bracketed sequences of 9 shots each) to process, where the sky was crystal clear without any high cloud visible. The exposure time for each sequence bracketing was ranging from 1/125s, 1/60s, 1/30s, 1/15s, 1/8s, 1/4, 1/2s, 1s, 2s at ISO100, plus additional fast exposures of 1/4000 for C2 and C3 (Prominences and Baily’s Beads). 93GB of images were acquired just for this setup, being 1446 calibration frames such as flats, darks and bias (in a total of 65GB). Images used were captured during 1 minute and 28 seconds of the Maximum, during the 4 minutes and 19 seconds of Totality as seen from my location in Clarcksville, Texas.

Fine Art Prints – Available to ORDER

I hope you enjoy it as much as I do, and if you still want to support my work as an independent artist, you can buy this image as a Fine Art Print, a piece of Art to bring some magic to your sweet home! I will be deeply grateful for your kind support. I have created a special limited Edition of this Print supplied with a signed & numbered Certificate of Authenticity, global delivery with tracked & insured shipping, in a carbon neutral sustainable production, packaging and shipping. Explore the size options and prices by clicking on my Print gallery. Meanwhile, you can sign-up my newsletter to get early access of future Print releases.