If an asteroid comes that will actually hit the Earth, the last thing the governments are going to do is tell people. Forget that "Deep Impact" and "2012" bullshit. People that they would want to live (assuming these dumb bastards have a plan that was created by someone smart and that plan isn't implemented by fuckups) have already been selected and probably already informed. If one hits, that is going to be it for the majority of us.