I’ve seen this photos of this phenomenon before but I don’t remember what it actually is. I believe @Troll once posted a nice shot of a Russian stage pluming (is that even a word?) near him. Someone please refresh my memory!
So the shot sucks but that wasn’t the photographer’s (our IRO’s) fault. We had the lights turned up to facilitate a crewrest swap. Everything in the shot except the little blurry bright spot and a couple of stars are windscreen reflections. The plum itself looked much bigger than the shot. It covered a portion of the horizon equivalent to the palm of my outstretched hand. We were approximately 50N40W heading east. In addition to the primary plume, there was a second, dimmer cone of light about 1.5 times my whole outstretched hand to the right of the primary object, on the side of its apparent direction of flight towards the horizon (east).
It’s a real word. To me, it means that my understanding is so weak that I am unqualified to even ponder at its mysteries. Google will tell you that it is something “that eludes precise evaluation”. That of course is not true of space flight. Unless you are me.