Answer:
My days are numbered.
I am a mother from a family of eight. Spins around all day despite my weight. Had a ninth sibling before founding out it's fake.
lighter than feather and softer than silk yet the strongest man in the world cannot hold me for more than a few minutes.
Sometimes I fly as fast as the speed of light. Sometime I crawl as slow as a snail. Unknown until I am measured but you will certainly miss me when Iām gone.
Open me, and you can't see me without a mirror. Close me and you can't see me at all. What am I?
What never gets any wetter no matter how hard it rains?