Name: Date: Solstices, Equinoxes, and the Seasonal Cycle Lab The wood stick in your model represents the axis about which the earth rotates. One end is north and the other end is south. You have placed a line around the center of the ball (the earth’s equator). Looking at a globe or a map, find your approximate latitude, and place the tack or dot there on your model. (For example, Cuddy, Pa at 40.3492° N, 80.1606° W, so placing the tack not quite halfway between the equator and the North Pole is an acceptable approximation.) As best you can try to tilt your model 23.5 degrees. (use a protractor). Warm-up: Model a “Day” on Earth Turn your axis so that the earth spins counterclockwise (when viewed from the north) for one rotation, and hold the flashlight so it is point at the equator. What do you notice about the dot as you spin your model? IMPORTANT: Each group member will need to take turns assisting the other members in modeling the seasons. Modeling the Seasons: Step 1: Locate Polaris, better known as the North Star. All axis should point to Polaris throughout the activity. Step 2: Set up the flashlights in the center of your small group. Before darkening the room, make sure all earth models are oriented correctly toward Polaris. Darken the room. Step 3: Have each group member move to one of the four seasonal positions around the lamp (or one student at each group should me holding the flashlight in the center): December 21, March 21, June 21, and September 21. It should look like this if seen from above:

Step 4: Have each group member model a day at each position. 1. Answer the following questions for each date. Each response is worth 1 point. CREATE A SINGEL A GOOGLE DOC WHERE YOU WILL RECORD YOUR ANSWERS. December 21: 1. What fraction of the day is the dot in the light? 2. What fraction of the day is the North Pole in the light? 3. How is the light from the sun striking the dot? Is it direct or at an angle? March 21: 1. What fraction of the day is the dot in the light? 2. What fraction of the day is the North Pole in the light? 3. How is the light from the sun striking the dot? Is it direct or at an angle? June 21: 1. What fraction of the day is the dot in the light? 2. What fraction of the day is the North Pole in the light? 3. How is the light from the sun striking the dot? Is it direct or at an angle? September 21: 1. What fraction of the day is the dot in the light? 2. What fraction of the day is the North Pole in the light? 3. How is the light from the sun striking the dot? Is it direct or at an angle? Modeling a Year: After you each of your group members have modeled the four dates: December 21, March 21, June 21, and September 21, they’ll have modeled a year: one earth revolution around the sun. Conclusion Questions: Each response is worth 2 points. Please answer in complete sentences. CREATE A SINGEL A GOOGLE DOC WHERE YOU WILL RECORD YOUR ANSWERS. 1. Revisit the year stations. Notice the angle at which the sun strikes your dot during the summer versus during the winter. 2. In which season are you the most likely to get sunburned? Why? 3. Imagine you’re living on the equator. How would you describe the change of seasons? 4. Now imagine that you’re at the North Pole in the summer. What path does the sun take across the sky?

5. What special aspect of the sun's position or movement do we mark with the solstices and the equinoxes? 6. What would seasons on the earth be like if the axis weren't tilted? Sun Dagger Petroglyph The Chacoans were an Ancestral Puebloans that lived in the American Southwest between 900 to 1350 AD. They lived in a range of structures that included small family pit houses, larger structures to house clans, grand pueblos, and cliff-sited dwellings for defense. They had a village on Fajada Butte, which rises 135 meters above the canyon floor. Although there is no water source on the butte, there are ruins of small cliff dwellings in the higher regions of the butte. Analysis of fragments of pottery found on Fajada show that these structures were used between the 10th to 13th centuries. They carved Sun Dagger in the walls of butte. Visit the link on the class homepage and complete the activities relating to the Sun Daggers. Sun dagger petroglyph: http://www.exploratorium.edu/chaco/HTML/sundagger.html

Complete the following questions once you have finished the activities. Each questions is worth 2 points. CREATE A SINGEL A GOOGLE DOC WHERE YOU WILL RECORD YOUR ANSWERS. 1. How do you know when the seasons are changing?

2. Do you use signs that the Chacoans may have used?

3. What modern signs tell you that the seasons are changing?

4. How does the change of the seasons affect you?