A Sense of Direction
Next develop a game of elimination. In each successive round, tell students how closely they must estimate the
given direction in order not to be eliminated. For the first rounds, use the cardinal directions so that students
can become familiar with compass readings in degrees (i.e., north
The Stars as a Compass
Few people realize that the night sky rotates in a complete circle every 24 hours. All the stars appear to move around the sky in a big circle except one-the North Star. This is because the North Star is positioned very near the North Pole, the axis of the Earth's rotation. Therefore, the North Star seems to stay in the same place all night. Explorers have used the North Star for navigational purposes for centuries. It might be a surprise to know that animals can use stars as a compass too.
A. Ask students how they might use the North Star as a compass. Show them how to locate the North Star in the night sky. To do this they must be able to find the Big Dipper. As shown in this diagram, two stars in
the bowl of the Big Dipper point to the North Star.
B. Have students make two sketches of the night sky. The sketches must be drawn on the same night, preferably one at dusk and the other at dawn. (If this is not possible, make certain that the sketches are drawn at least four hours apart.) Each sketch must include the position of the Big
Dipper and the North Star. Students should draw as if they are lying on their backs and looking up at the sky. Each sketch should indicate the directions north, east, south, and west. Students should also note the time the drawing was made.
C. The next day, help students visualize the full rotation of the stars by making paper models. Each student should draw a 24-hour clock on a circle. On a smaller disk, have them draw the North Star and Big Dipper. A paper fastener can be used to connect them. By rotating the model, students can compare the timings of their drawings to the position of the stars.
The Sun as a Compass
Humans are able to use the sun for a rough sense of time and direction. We know the sun is in the east in the morning, in the south at noon and in the west in the evening. In order to use the sun for navigational purposes, migratory animals must use far more precise and sophisticated methods.
Remember that while the North Star remains stationary, the sun is a moving target. It "moves" across the sky during the course of a day-so animals must have mechanisms in place to compensate for this.
A. In this activity, students measure the changing position of the sun in order to understand the difficulties involved when using it for navigation. Have students draw the sun's position in the sky at three distinct times during the day, i.e., at 8 am, noon, and 3 pm. Using a compass, have them measure the sun's bearing at each time.
B. To emphasize the complexity of relying on the sun for a sense of direction, repeat this process six to eight weeks later. Before going outside, have students review their previous measurements and predict the sun's location. Then, go outside and draw the sun's actual position and bearings.
Caution: So that students do not look directly at the sun, have them use their shadow and correct their bearings by 180º.
C. Encourage students to researchsuch topics as polarized light, sundials, human navigation and orienteering.
The Earth's Magnetic Field as a Compass
Perhaps the most astonishing discovery in navigation research is that animals may have a "sixth sense" that helps them navigate. This sense lets them detect the Earth's magnetic field.
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