Arc of light across the sky created by a high-altitude fuel dump from an orbiting rocket. It looks like a huge comet or an odd auroral arc. In this case it was from the upper stage of a Chang Zheng 6A rocket launched from China just 3 hours earlier that was placing three Yaogan satellites into polar orbit. This is what it looked like to the eye. It appeared first much higher across the east, but the whole arc was moving from south to north. Photographed from southern Alberta, Canada on 10 September 2023.