“If you are in the SF Bay Area, look West and about 30 degrees up, and you will see a very distinct and thin bright arc of light. It looks like the thin tail of a comet. I thought it was a plane or satellite but it’s not moving. Is it a comet?”
I did not see it tonight, checking the same patch of sky.
Compared with photos online of Pons-Brooks, this was not similar.
What I saw last night was not parallel to the horizon. It was a series of blue-green threads of light reaching for the zenith and focused and brighter at the zenith. I wonder if it might have been trails of space junk descending into our atmosphere. Was it a searchlight of terrestrial origin? It was too long for that, and had no clouds to project onto. Skies were clear.