Salam Joseph,
Many thanks for the explanation. However, I am still convinced the thread (khaytu) refers to a physical thread (or string) based on the word abyadu (white).
Look at the dawn sky. Do you see any white? Even the clouds, usually white in the daytime, looks orange (or reddish, or pinkish) at dawn.
Anyway, I could be wrong. Maybe, you could see the white streak in the sky at dawn in the desert.
BTW, have you tried out the experiment I suggested.
Once again, peace.