Cassini tribute - Jagged shadow artifacts with Cycles

I am making a little Cassini tribute as a long term project, going for realism, but higher dynamic range and a little artistic freedom. Feel free to poke at it and say what your thoughts are on what looks real and not.
But I have a main problem. I have one sun lamp in the scene, with 3 as a strength and angle between 8 - 15. But no matter what I do I get these jaggedy triangle shadows, and I also get them on some of my other scenes. Any ideas how to get rid of them? I also seem to get some fireflies like thing under the rings.


removed by popular demand

It looks like the terminator bug raytracing render engines suffer from. Unfortunaly you can’t fix it.
As a workaround, you can apply the subsurf modifier to make it look less noticable.

Didn’t know about this, subdividing it more definitely helped, thanks. Yeah I should try Eevee more, but it sometimes has some really weird shadow artifacts as well, and I don’t always figure them out.