# 50. MAPPING A PLANET’S MAGNETIC FIELD

SUBJECT: Science
GROUP SIZE: Large or Small
TIME: 60 minutes
TYPE OF ACTIVITY: Teacher Demonstration or Student Activity
TEACHING STRATEGY: Guided Discovery Expository
CONCEPTS: Magnetic Field Planetary Model Magnetometer
SKILLS: Experimentation Recording and Interpreting Data
Objectives: To model how an aircraft or space craft can map the magnetic field of a planet; to be able to produce a map of the magnetic field of a planetary model.

Materials: Two maps of an area, one covered with plastic; at least one magnetic compass; a styrofoam ball; a clear sheet of acetate; an overhead projector; pen or grease pencil; several small bar magnets; iron filings in a shaker bottle.
Teacher Background Information:

By flying through a planet’s magnetic field, a craft can actually map a magnetic field’s size, direction and strength using a magnetometer. Numerous NASA space launches, particularly in the Explorer series, have gathered such information. Specially equipped high-flying aircraft have also been used to map Earth’s magnetic field and to develop the techniques used on the spacecraft.
Procedure:

Experiment A.

1. Place a magnet under the plain map.
2. Lay the acetate sheet on top of the map.
3. Make several passes over the map with the “magnetometer” (compass).
4. Make note of the direction of the compass needle. Use the laminated map to record the findings with a grease pencil.
5. Check your findings by shaking metal filings on the plastic sheet covering the original map.

How did your findings, using the compass, compare with the pattern formed by the filings? Does this pattern appear similar to what you would expect to find on the Earth?
Experiment B.

1. Place a magnet in the styrofoam ball.
2. Set the ball on a cup so that it is supported away from the surface of a table.
3. Use the compass to make several orbital passes around the “planet”.
4. Make a simple sketch of the magnetic field of the “unknown” planet.
5. You can test your findings by using the plastic sheet and iron filings again.

Adapted from educational material s available from NASA Spacemobile program

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