Stitching on Solar Eruption

I didn't ruminate very long before I decided to go back and do some more free-motion stitching on this piece. It's a slow process, requiring thread color changes as I go, and my biggest frustration is that the top thread keeps breaking. Could be tension problems, or thread that is too old. I changed my needle before I began, so that's not the cause. At any rate, here are a few closeup shots: