Currently the "solar disc" function is a bit simplistic, and the facility for dealing with ultra-bright surfaces is also not yet optimized. So for extremely bright things like the sun, where a proper corona or halo isn't making the edges smooth, you get very sharp edges. This can also happen with very bright skies against the terrain or luminous surface edges. We plan to implement better antialiasing of such bright elements in the future, possibly including "bloom" or other such effects to better deal with these problematic areas.
- Oshyan