That's just not good. Not good at all.
Why isn't it good? Simply because we can't panic ahead of time. Armageddon isn't any fun if you can't panic. All you would have is the Sun being blotted out by a rock the size of Walla Walla Washington and then the last thing you see is your feet as said rock flattens you to mush. Hardly any time for panic in the streets.
Obviously we could divert an asteroid headed our way. I doubt that there is any possibility we ever would though. Republican fanatics would be putting Hitler mustaches on Obama for trying to save us. Republican congressmen would deadlock on the price for diverting an asteroid that would meet their need for Armageddon. Even the Democrats would be spouting 'laws of nature' and we would still be so much mayonnaise between crunchy earth and crunchy asteroid.
This is also bad for the fear mongers and end of the world cults. It would be absolutely incredible to have an honest to god confirmed threat. No more guessing. Just honest info and a date for the end of the world plus or minus four and a half minutes.
Please O' please, write your congressman, especially the Republicans, for some money for NASA. We need our advanced warning of the end times!