Astroids

J: Lisa, why did the assroid kill all the dinosaurs
L: because it was so big that it was like a giant bomb hitting the earth
J: Is a assroid going to hit our house
L: No, don't worry, we're safe
J: Why are we safe
L: because we have scientists that watch the skies and make sure that big astroids don't head toward earth
J: but why did it hit the dinosaurs
L: Because they didn't have scientists or computers or anything...they just ate, pooped, slept, and played and that is ALL they did
J: *giggle*
L: We do a lot more than that, don't we?
He looks at me and starts counting on his fingers
J: yeah, we eat, sleep, poop, and watch commercials...so we're safe. He nods his head satisfied.

There you go...summed up by a four-year-old...we are safe from astroids and are free to eat, sleep, poop, and watch commercials.