Moving artifact in cloud during animation

[jmadden]

I haven't found a similar issue on the forums so I'm asking for some guidance.
I'm doing an animation and I noticed that there is what appears to be a line that moves across my clouds that changes their brightness. 

I've attached a video of what this looks like, you can see the clouds near the terminator changing brightness along a line, it's subtle but stands out in the full video. 

The animation is simple, the clouds are static, just the camera is moving. I'm wondering if this has something to do with the quality clouds are rendered based on distance to the camera? Like as the camera gets further away the quality is reduced and can be seen during an animation. The clouds are a single v2 cloud layer with 0.1 quality so they render quite quickly but maybe cause issues like this. My defer clouds/atmo is off and anti aliasing is set to 6. Lots of quality corners being cut for the sake of render time.

Is there any way I can fix this without drastically alerting the scene? I'd like to just be able to re-render the 5 or so frames where this line can be seen instead of redoing the entire sequence. Maybe there is a way to make the transition more gradual and less noticeable. Any insight would be appreciated. 

Thanks

[jmadden]

Just wanted to add an update for posterity. 
I figured out the issue, it seems as though when the camera is ~1e7 away from the cloud layer there appears to be a change in how it gets rendered. As the camera was moved above and below this distance it created a line at that 1e7 distance. The clouds further rendered one way and the clouds closer rendered another. For the fix, I changed the camera path to always be within 1e7 of the nearest point to the planet and there was no line. 

Here is the final animation. 

and the rest of the stills on Artstation https://www.artstation.com/artwork/eaP04Y

[WAS]

The background sphere radius is also -2e+08 so if you're outside it, you would be able to see inside due to it's inverted radius, but it would also mess things up. THis happened to me once, but it was more chaotic then your example, so probably just a point of origin issue, I guess.

Though I did a planetary solar system mock a long time ago at true scales, where as the "solar system bubble" (background sphere) was -1.4373e14 and was able to render out stills. I never did get to animate this as I was on freeware and my backup HDD is corrupted. Need to send it in for recovery cause I've tried every tool I can think of down to boot-time command line tools. Anyways, just saying wonder if you clipped the background sphere.