[blam]

Did Asteroids And Comets Change The Tides Of Civilisation

[P.O.E.]

I've often wondered if, (given the proclivity towards astronomy by so many ancient cultures and the trouble they went through to build enduring monuments incorporating such knowledge) the ancients weren't trying to warn us of just such a calculated future event.

E.g., our system wandering through a cloud of debris, a planetary alignment (such as one described here where Jupiter's gravity gives a just-so push) or some long-period recurring event.