What happens when meteorites hit the earth?
	Meteorite impacts are a major force of geologic change on planets and satellites in our solar system!

Craters on Earth and other bodies in the solar system.

Perhaps the most pervasive geologic activity within our solar system is the impact of smaller objects with larger objects to create craters.  We can see craters on the moon with the naked eye, and there are craters on all the solid planets and satellites we have observed so far in our solar system.  There are even impact craters on Earth!

Volcanism is another major geologic process acting to reshape our earth, and we have observed evidence of volcanic activity on other planets and satellites in the solar system.

Impacts of meteorites and the activity of volcanoes can both produce craters on the surface of planetary bodies.  Images of these craters have been captured by various NASA missions to the planets and satellites.  Since geologists cannot yet go to other planets to conduct field work for themselves, they have to be able to piece together the geologic happenings there by observing and interpreting the images.  Planetary geologists use what they know about earth's geology to help interpret what happened on other planets.

Student Activity:

In this activity, you will conduct experiments to simulate the creation of both kinds of craters.  After making observations on the similarities and differences between impact craters and volcanic craters, you will examine photos of craters on Earth, Venus and Mars, and use what you observed in your experiments to evaluate how each crater was formed.

Creating Impact Craters*:  Models of impact craters can be created by dropping round objects onto a softer surface of unconsolidated material.  A simple method of doing this using everyday materials is to fill a small box or bowl with flour, sprinkle powdered cocoa on top to provide color contrast, and drop marbles onto this surface.

Creating Volcanic Craters**:   There are different types of volcanic craters.  One is produced by pyroclastic material ejected by a volcano piling up around the vent producing a cinder cone; the crater is the central depression of the cone.  A pit crater is produced by collape of the surface when magma subsides to a lower level in the earth.  Another much larger type of volcanic crater, more properly called a caldera, forms from collapse of a large area of the surface when a large volume of magma is ejected.  A model of a pit crater or caldera can be created by inflating a small balloon attached to flexible tubing closed off with a hose clamp and burying the balloon in a mound of sediment or flour.  Opening the hose clamp and releasing the air from the balloon will cause collapse of the center of the model volcano.

Interpreting the origin of craters on Earth, Mars and Venus:  After you have created both types of craters experimentally and recorded your observations, take a look at the following photos of craters found on Earth, Venus and Mars.  Write a brief description of each crater.  Which ones were likely formed by meteorite impacts?  Which ones were likely formed as a result of volcanic activity?  Are there any features that could be a result of both?  Would it be possible for volcanic activity to be triggered by an impact?

Click here to see photos of students in a Physical Geology course engaged in this activity.
 

Images of craters on Earth:
 

E1. Diameter of crater is 0.9 km.	E2.  Diameter of crater is 0.2 km.
E3. Diameter of crater is 0.2 km.	E4.  Diameter of crater is 1.2 km.
E5.  Diameter of crater is 10 km.	E6.  Diameter of lower crater is 36 km.

Images of Craters on Mars:

M1.  Diameter of largest crater (lower left) is 18 km.	M2.  Diameter of  crater is 18 km.
M3.  Diameter of  crater is about 50 km.	M4.  Diameter of largest crater (center) is about 70 km.
M5.  Diameter of  largest crater is 12 km.	M6.  Diameter of largest crater (right center) is about 60 km.

Images of craters on Venus:
 

V1. Diameter of crater is 86 km.	V2.  Diameter of crater is 90 km.
V3.  Diameter of crater is 30 km.	V4.  Diameter of largest crater (right) is 72 km.

Photos courtesy of NASA.

* Note to educators:  There are several websites where cratering activities are described for use in secondary education, but they can be easily adapted for introductory college geology courses.  See for example Activity 6 in NASA's Exploring Meteorite Mysteries or the activity described within NASA and  Lunar and Planetary Institute's  Lunar Impact Crater Geology and Structure. **  The Volcano World website describes ways to create model volcanoes. Some of them can be adapted for introductory college geology courses.

Go to NASA/UNCF Project:  Infusing Space Science Into a Science Core Curriculum Through a Community of Scholars
Go back to Meteorites! page

Department of Earth Science
Northeastern Illinois University
 

Text of this page © 2003 The NASA/UNCF Project,  Northeastern Illinois University
Last updated April 25, 2003.