[brunosan]

The part that is confusing is highest resolution (1) full-disk and (2) outer atmosphere: (1) "Full-disk" is clear to understand: the higher the resolution, ^2 the work to make it also full-disk (especially when the Sun rotates differentially and evolves in high-cadence, so you gotta be fast. (2) "Outer atmosphere" is also tricky as only few wavelengths see the outer atmosphere. The vast majority of the light comes from the "surface" or photosphere (hence the name). In this case surface, the highest resolution is roughly 0.05 arcsec or 50km/pixel. But to see the outer parts, you have to do to emission of elements like Iron that only emit when highly ionized and super high temperatures (those are the special characteristics of the sun's outer atmosphere... yes, it's way hotter than the surface, just WAY less dense). Those emissions happen in the Ultraviolet, 17 nanometers, like the caption says. That's like 50 times smaller wavelength. Angular resolution is proportional to wavelength (1.22*wavelength/Diameter) which is on the order of 1000 km/pixel (but linear resolution makes less sense since the atmosphere is such a 3D shape... it's better to say 1 arcsec of resolution).

I might be too biased (I'm a solar physicist) but the explanation above makes the image way cooler and they should have added it): The most detailed image of the Sun's metal corona :D