Throughout my life I have heard many rumors of asteroids hitting earth or the moon but I've always wondered what kind of damage an asteroid could really cause. The size of the explosion would be most impacted by the kinetic energy of the object that caused it. This would mean that the mass and the velocity of the asteroid would be the main factors in the damage. The average speed for asteroids approach either the earth or the moon is around 17km/hr. Now that we have the speed, how can we find the mass of an asteroid traveling that fast through outer space? Mass is calculated through the density and diameter of the asteroid. The typical diameter for these objects are around a few hundred miles and the densities range for 3-8g/cm^3. We can then find the kinetic energy and the angle at which the asteroid will strike the surface to determine how much damage any given asteroid will cause.