They are some strange ring reflections as seen from the surfaces of all the gas giants. It shows up especially on Saturn, the rings of Uranus and Neptune are darker and are less noticeable than on Saturn, but these reflections are there. This issue first showed up in versions 13.0 – 13.3 of Stellarium. I’m sorry for not reporting this issue sooner.
These reflections show up while looking east or west, but as you scroll completely around 360 degrees using your arrow keys, these reflections disappear at the north and south. On Saturn if you look at these reflections and advance the time and along with the rest of the gas giants through a complete rotation you will see them disappear because of the rings shadow, and then they reappear. “See screenshots links.”
During the day time on Saturn.
http://i862.photobucket.com/albums/ab186/bluecatfish/S1_zpsoymgtwhz.jpg
During the night time on Saturn.
http://i862.photobucket.com/albums/ab186/bluecatfish/S2_zpstxx4mvkt.jpg
Graphics card: PNY NVIDIA Geforce GT 630 2GB DDR3.
NVIDIA: driver version. 350.12
Apparently projection type matters. I can reproduce this pattern only in perspective mode, but other modes also give bad foreground artifacts. (Confirmed on Win7/NVidia 580M)