In fairness, the odds of an asteroid hitting so close to a major city is so small, that an intentional alien attack should not be entirely ruled out. A berserk

In fairness, the odds of an asteroid hitting so close to a major city is so small, that an intentional alien attack should not be entirely ruled out. A berserker in far solar orbit could conceivably stunt human development every couple thousand years with an asteroid, while a more effective extermination ship is being dispatched.