  Impact craters exist on various solid objects in the planetary system. A
simplified analogy of the process of their formation is here analyzed by
standard solid state physics and the so called dynamic quantized fracture
mechanics. An expression which links the crater volume to the parameters of the
impactor and the target is obtained within the two approaches. For low impactor
energy, this expression is of the same mathematical form as the one resulting
from recent experiments.It is shown that the formation of an impact crater is
possible even without heating of the target, if the critical stress in the
target satisfies certain conditions. The critical value of the stress needed
for the occurence of a fracture is calculated for three craters: two
terrestrial and one lunar crater. The approach presented here uses only
measurable material parameters, and is therefore more realistic than the
treatement of the same problem using the cohesive energy of materials.
