PURPOSE: To illustrate how a crater forms as a result of an impact or a blast from below.

DESCRIPTION: (left photograph above) Drop a steel ball onto a dish of sand. The ball becomes partially buried and a crater forms.

(right photograph above) Bury the end of the hose in the sand using the plastic strip attached to the end of the hose, and smooth out the sand. Using lung power, blow in a blast of air and notice the crater that forms.

A generation ago there was a debate among geologists and astronomers as to the origin of lunar and terrestrial craters. This demonstration illustrates two ways in which craters can form.

SUGGESTIONS:

REFERENCES: (PIRA 8A20.30)

EQUIPMENT: Dish of fine sand, steel balls, tube attached to plastic sheet for positioning in the sand; please ask for Tensor lamp and video camera for TV projection if appropriate.

SETUP TIME: 5 min.