The end, unless you're a small proto-mammal ;).

An object (depending on consistency) of about 100m is enough to wipe out a city and do enough damage to the environment. Something of 8-20km is in the same category as what wiped out the dinosaurs (10-15km).

It’s going at 68km/s so I think even microbial life could be in trouble.

Seems like it arrives with a bit more energy than a 10 on richter scale: https://www.edinformatics.com/inventions_inventors/richter_s...

No, I can’t really imagine what that means, either.