[C210N]

A large rock could indeed wipe out civilization... the scenario would be darkening the atmosphere for a few years wreaking havoc on the climate. Case in point is the volcano, I think it was around 1888 or so, that caused the "year without a summer"; of course, the detestation would have to MUCHO larger than that. Another data point is the theory that dinosaurs were wiped out with a meteoric impact.

But, more to the point of this thread: Any rock big enough to do this is not going to be convinced to go elsewhere just because humans spend a bunch of trillions of dollars and devastate the global economy to alter its path. Not a single inch, or degree of trajectory, would it be diverted.

[gleeaikin]

Krakatoa was in 1883. Interesting factoid. I just read a book about Powell’s 1869 exploration of the Colorado River. The book mentioned that the record flow in the river was in 1884. Remember the 500 year floods in the midwest a year or two after Pinatubo which had a crater 3 miles in diameter.

A more severe event occurred about 74 thousand years ago when Toba Volcano in Indonesia blew up leaving a crater 18 by 65 miles. Scientist are now speculating that the human race was reduced to no more than 5 or 10 thousand individuals. I think this is based on DNA variation studies.