If this does happen, it will be fortunate, and it will come at an ideal moment in history.
The report says this object is 50 km in size and it would release 20 billion megatons. I say this will be fortunate because it will put the fear of God into the human race, and spur us to take the threat of asteroids seriously. It comes at an ideal moment because we have spacecraft orbiting Mars, and on Mars, so I do not think there will be any question we will see the impact, and measure the approximate size of it. There will be no doubts about it. If this had happened 50 years ago we might not have noticed. - Jed
