Asteroids sling through space, celestial debris of diverse origins, leftovers from the formation of the solar system, broken offshoots of parental asteroids or comets that have lost their glow. But if an asteroid were to smash into Earth, the result would meana global catastrophe and life on our Planet could come to an end. The explosionwould approach that of a million megatons of TNT- sixteen hundred times greater than the most powerful nuclear weapon ever tested (Barnes-Svarney 234)."Asteroid" is Greek for "starlike". They were given this name because early telescopes could see them only as points of light. The asteroid belt, between the orbits of Mars and Jupiter, contains tens of thousands of asteroids with diameters of a mile or more. The larger ones are spherical, but smaller ones, their cohesion greater than their gravity, are extremely irregular. There is no lower limit to asteroid size because they grade down to tiny rocks and particles of dust No asteroid is big enough to hold an atmosphere (Gardner 5).Almost all asteroids are confined to the asteroid belt, but many wander far beyond the orbit of Jupiter, and others plunge inward past the orbit of Venus. It is estimated that more than a thousand asteroids at least a mile wide are "Near Earth Objects" (NEOs). Some are three or more miles wide. They pose a monstrous threat to humanity if they come close to Earth or hit it (Gardner 16).According to a report sponsored by NASA in 1992, "The Spaceguard Survey: Report of the NASA International Near-Earth Object Detection Workshop", the hazardsfrom asteroids can be divided into three broad categories that depend on the size and/or kinetic energy of the impactor (Barnes-Svarney 225).A Category 1 impact usually breaks apart before it reaches the surface and it is usually between 10 and 100 meters in diameter. The explosion of the object creates the kinetic energy equivalent to about 50 to 100 kilotons of TNT. The Category 2 imp...
