http://www.moviemistakes.com/blogpost19This makes for cheerful viewing - a simulation of what would happen if a 500km-wide asteroid hit the earth. Short version - enjoy the pretty light show then kiss your arse goodbye. This reminds me of the closest thing to a motivational poster I own, which is currently hanging above my bed (I used to have a picture of a nuclear explosion there - honestly - but I found that unreasonably raised expectations). Anyway, it's titled "Wishes", with a picture of a falling star - all very inspirational, until you read the caption:
"When you wish upon a falling star, your dreams can come true. Unless it's really a meteorite hurtling to the earth which will destroy all life. Then you're pretty much hosed no matter what you wish for. Unless it's death by meteor." There's a message for us all there.