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by zokier 1841 days ago
0.1mm is not very smooth. According to wikipedia, 150 grit sandpaper has average particle size of 90-100µm

edit: of course there is vigorous internet commentary about billiard ball smoothness compared to earth:

https://possiblywrong.wordpress.com/2011/01/03/is-the-earth-...

https://skeptics.stackexchange.com/questions/10763/is-earth-...

https://billiards.colostate.edu/faq/ball/smooth/

Which mostly seem to agree that earth definitely is not as smooth as a (new) billiards ball, but there is lots of debate about the details.