If you're easily disturbed by doomsday scenarios, you may want to move on to the next blog. I am not responsible for any loss of sleep or nightmares this might cause.

Here's an amazing simulation from the Discovery Channel of what it would look like if earth were to be impacted by an incredibly large asteroid. Long story short, it would be game over. Earth's entire biosphere would be sterilized by something this big.

http://www.youtube.com/watch?v=P2RGt-qGFkg

The one thing I disagree with is how clear the air is at the end. Trillions of tons of pulverized rock would make the atmosphere opaque, I bet. But the sight of an earth devoid of life or oceans with a glowing, exposed mantle is rather alarming.