“Suppose that there was a button you could push and you could light up all the Earth-crossing asteroids larger than about ten meters, there would be over 100 million of these objects in the sky, all of which are capable of colliding with the Earth and all of which are moving on slightly different courses through the sky at different rates. It would be deeply unnerving.”

Steven Ostro of the Jet Propulsion Laboratory; Bill Bryson, A Short History of Nearly Everything (New York: Broadway, 2003), 194.