Solar surface map: Solar System Scope / INOVE
https://www.solarsystemscope.com/textures/
Licensed under Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/
Source image is unmodified; the website applies animated projection, colour and lighting.
Distributed source mirror: https://github.com/Sanghel/solar-system-3d/blob/develop/public/textures/sun.jpg

4K source mirror (4096 x 2048): https://github.com/fury-gl/fury-data/blob/master/textures/8k_sun.jpg
SHA-256: f22b1cfb306ddce72a7e3b628668a0175b745038ce6268557cb2f7f1bdf98b9d
The upstream filename says 8k; actual image dimensions are 4096 x 2048.