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STANYS Workshop - Fall, 2005 Name: ______________________________

Exploring Earth’s Seasons

Hypothesis:

1. State your hypothesis as to what causes Earth to experience seasons (e.g., warmer in summer, colder in winter).

Procedure 1: Place globe at point A (Figure 1), with the North Pole facing the corner of the table. Now, measure distance from lamp to point A. Next, move the globe to Point B and, again with the North Pole facing the same corner of the table, measure the distance between the lamp and Point B. Record these distances in Table 1 below. Let us assume that we are in New York State. Position New York so that it faces the “Sun” (the lamp). Indicate which season occurs in New York at each position in accordance with your answer to question 1.

Note: We keep the North Pole facing in the same direction because this is the position it maintains as the Earth orbits the Sun. It always points toward Polaris – the North Star.

Figure 1. Positions A and B of globe and lamp for measurement of distances. The North Pole points in same direction at each position. Distances may be measured from bulb to globe or from base of globe to base of lamp. Be consistent in how you measure!

Table 1: Distances and Inferred Seasons
Distance from Lamp to Point A	Distance from Lamp to Point B

Season:	Season:

Ebert, Johnsen, Cohn, Barnabee & Kaszubski – SUNY Oneonta

Procedure 2: Now, let’s get ready to test your hypothesis (answer to question 1and prediction in Procedure 1). With the globe at Position B, turn the globe on its axis so that New York faces the lamp. Insert a piece of cardboard between the globe and the support arm to act as a “brake” which will keep the globe from turning. You should place the cardboard near the South Pole so that it does not interfere with our next step.

Procedure 3: Place the solar cell on the Velcro patch that is nearest to New York State (45º North) (Figure 2). Re-orient the globe so that it is in the same orientations shown in Figure 1. Re-insert your cardboard “brake.” Next, turn on the lamp and record the reading on milliammeter which is connected to the solar cell. The reading on the milliammeter is a direct measurement of the amount of light (“Solar Energy”) reaching the Earth at that point. Record your answer in Table 2 below. Also, be sure to transfer your measured distances from Table 1.

Figure 2. Solar Cell and Milliammeter

Table 2: Milliammeter Reading and Distance from Lamp	Position A	Position B
Reading from Milliammeter
Rank of Reading (Indicate High or Low after both measurements)
Distance from Lamp (from Table 1 above)

Procedure 4: Move the globe back to Position A and repeat Procedure 3. Be sure to record your data in Table 2. Make sure the North Pole continues to face in the same direction!

Ebert, Johnsen, Cohn, Barnabee & Kaszubski – SUNY Oneonta

Compare your results (Table 2) with your prediction (hypothesis) in Question 1 and Procedure 1.

2. Are your data (Table 2) consistent with your prediction? Explain your answer by describing your results with what you predicted. In other words should you accept or reject your original hypothesis?

3. What variables were tested in the experiments described in procedures 3 and 4?

4. Based on your results from this experiment, write a statement that describes the cause of Earth’s seasons. Be sure to include in your answer references to both distance and relative position (tilt) of Earth’s rotational axis.

5. In our model, we changed the distance between the Earth (globe) and the Sun (lamp) by 20%. Earth’s real orbit around the Sun only changes the distance by 3.34%. What effect, if any, do you think this change in distance has on the seasons?

6. If the axis of inclination is perpendicular to the sun (as in Figure 2), what time of year (season) could it be? Explain your answer.

7. If Earth was struck by a large asteroid and the axial tilt was changed to 40 degrees, what effect do you think this would have on Earth’s seasons? Explain your answer.