Julie, On the subject of asteriods and Patrick help me out here. In the next decade an asteriod will pass between the earth and moon so close, that according to Sky&Telescope we will here the hissing while it passes. Should be an impressive spectacle, maybe that will wake the world up the dangers of asteriods. The massive fires caused by impacts of asteriods are the events that have dramatically increased CO2 levels in the earths 4 billion year history. There is also theory out there that the moons formation may have been influenced or even created by a massive asteriod impact. Of course we can thank asteriods for our existence by getting rid of the pesky dinosaurs and make way for us mammals. What species will repalce us? Erik