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Student Exploration: Seasons: Earth, Moon, and Sun
Vocabulary: altitude, axis, azimuth, equinox, horizon, latitude, revolution, rotation, solstice
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
1. Suppose you were stranded on a desert island without a calendar or clock. How would you know when a day, a month, or a year had passed? ______
______
2. How could you tell what time of year it was? ______
______
Gizmo Warm-up
Thousands of years ago, people told time by looking at the sky. You may not think about it, but you probably do this as well. For example, you know a day has passed when the Sun rises, it grows light outside, and then Sun sets again.
In the Seasons: Earth, Moon, and Sun Gizmo™, you will learn how you can relate the passage of time to different astronomical events.
1. Drag the speed slider all the way to the left. Click Play () and observe the SIMULATION pane.
A. What happens? ______
______
B. Click on the 2D VIEW tab. What do you see? ______
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C. Click on the DAY GRAPH tab. What do you see? ______
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D. Click on the SHADOWS tab. What do you see? ______
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Activity C:Sunrise and sunset times / Get the Gizmo ready:
· Click Reset.
· Select the DESCRIPTION tab. /
Question: What factors affect sunrise and sunset times?
1. On your own: Latitude is a location’s distance north or south of the equator. You can find the latitude of your town at the following site: http://www.satsig.net/maps/lat-long-finder.htm.
What is the latitude of your town? ______
Use the Latitude slider on the DESCRIPTION tab to set the Gizmo to your town’s latitude.
2. Collect data: Select the DAY GRAPH tab. Click Play, and observe. Solar intensity goes up at sunrise and goes down at sunset.
Click Reset. Use the slider on the controls pane to change the date to March 21. Click Play, and then click Pause after the sun sets. Use the graph to record the approximate sunrise and sunset times in the table below. (Note: The Gizmo does not take Daylight Saving Time into account.)
Date / Sunrise Time / Sunset Time / Hours of DaylightMarch 21
June 21
September 23
December 21
Click Reset, and repeat the activity above for the other dates listed in the table. Then calculate the hours of daylight for each of the four dates.
3. Compare: How do sunrise times, sunset times, and hours of daylight change over the course of the year? ______
______
4. Analyze: Equinoxes are dates on which the daytime lasts as long as the nighttime. Solstices are the dates of the longest and shortest daytimes of the year.
A. Which two dates are equinoxes? ______
B. How does the amount of daylight during the summer solstice (June 21) compare to that on the winter solstice (December 21)? ______
Activity C (continued from previous page)
5. Diagram: Click Reset. Move the date slider to each of the equinox and solstice dates. Examine how moving the date slider makes the position of Earth on the SIMULATION plane change.
In the diagram at right, mark Earth’s position and the position of Earth’s axis on each date. Shade in the part of Earth not lit by the Sun.
6. Compare: Use the SHADOWS tab to compare the Altitude of the Sun on the summer and winter solstices. Draw the highest altitude the Sun reaches on each of those two dates in the graphs at right.
On which date does the Sun reach the highest altitude? ______
7. Collect data: Use the observations you have made to answer the following question: What do you think causes the changes in sunrise and sunset times over the course of the year?
______
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8. Hypothesize: How do you think latitude affects sunrise and sunset times? ______
______
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9. Collect data: Select the DESCRIPTION tab. Move the Latitude slider back and forth to see how it changes the red dot’s position in the SIMULATION pane.
Click Reset. Set the latitude to 89°. Then use the DAY GRAPH tab to fill in the table. Repeat for the other latitudes listed in the table.
Latitude / Sunrise Time / Sunset Time89°
45°
0°
-45°
-89°
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What causes the differences between the sunrise and sunset times at different latitudes?
______
10. Repeat question two using latitude of 89, 45, 0, -45, and 89, instead of using the latitude of your town:
Latitude of 89°
Date / Sunrise Time / Sunset Time / Hours of DaylightMarch 21
June 21
September 23
December 21
Latitude of 45°
Date / Sunrise Time / Sunset Time / Hours of DaylightMarch 21
June 21
September 23
December 21
Latitude of 0°
Date / Sunrise Time / Sunset Time / Hours of DaylightMarch 21
June 21
September 23
December 21
Latitude of -45°
Date / Sunrise Time / Sunset Time / Hours of DaylightMarch 21
June 21
September 23
December 21
Latitude of -89°
Date / Sunrise Time / Sunset Time / Hours of DaylightMarch 21
June 21
September 23
December 21
Student Exploration: Greenhouse Effect
Vocabulary: global warming, greenhouse effect, greenhouse gas, heat flow
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
3. What do you notice when you get into a car that has been sitting in the Sun for a while?
______
4. Why is the inside of the car so hot? ______
______
5. How would things be different if the car’s windows were left open? ______
______
Gizmo Warm-up
Like the windows of a car, greenhouse gases play a major role in regulating Earth’s climate. Without the gases that trap heat in Earth’s atmosphere, Earth would be a frigid desert like Mars (average temperature -55°C). Too much greenhouse gas and Earth could be a fiery inferno like Venus (average temperature 450°C).
On the Greenhouse Effect Gizmo™, set the Greenhouse gases to 0% and the Simulation speed to fast.
1. Click Play () and view the BAR CHART tab. The temperature will go up and down every day, but try to look at the overall trend. What happens to the temperature over time?
______
2. Now set the Greenhouse gases to 100% and let the simulation run for a while. How does a maximum amount of greenhouse gas affect the temperature?
______
Activity:Heat in, heat out / Get the Gizmo ready:
· Click Reset ().
· Set Simulation speed to slow.
· Be sure the Greenhouse gases level is 10%. /
Question: How do greenhouse gases affect Earth’s climate?
1. Observe: Select the BAR CHART tab and click Play. After about 24 simulated hours, click Pause (). What do you notice about the heat flow into and out of Earth’s atmosphere?
______
______
2. Analyze: Select the TABLE tab.
A. At what time of day is heat flow into the atmosphere (Hin) greatest? ______
B. At what time of day is heat flow into the atmosphere (Hin) least? ______
C. Does heat flow out of the atmosphere (Hout) change during a day? ______
D. At what time of day is surface temperature highest? ______Lowest? ______
3. Predict: Click Reset. When you change the amounts of greenhouse gases in the atmosphere, which factor(s) do you expect to change? (Circle your answer/answers.)
Heat flow in Heat flow out Temperature
4. Experiment: Select the BAR CHART tab, and click Play. While the simulation is playing, move the Greenhouse gases slider back and forth. What do you notice?
______
______
5. Experiment: Click Play, and this time observe the GRAPH tab as you change the Greenhouse gases. What do you notice?
______
______
Activity (continued from previous page)
6. Draw conclusions: The influence of greenhouse gases on temperature is called the greenhouse effect. Based on what you have seen, how do greenhouse gases affect the heat flow into and out of Earth’s atmosphere?
______
______
______
______
7. Extend your thinking: Atmospheric concentrations of greenhouse gases such as carbon dioxide have risen dramatically in the past century. Most scientists agree that this has begun to result in global warming, a slow increase in average temperature worldwide.
What are the possible consequences of global warming?
______
______
______
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Note: The reason greenhouse gases raise the temperature of Earth’s atmosphere is similar to, but not identical to, the way that the glass in a greenhouse raises the temperature inside.
In a greenhouse, sunlight passes through the transparent glass and is absorbed by the plants and soil below. Heat is then radiated from plants and soil, which heats the air inside the greenhouse. The hot air is trapped by the glass. If the glass were not there, the hot air would mix with the colder air outside, and the result would be similar temperatures inside and outside the greenhouse.
In Earth’s atmosphere, greenhouse gases are transparent to visible light but absorb heat that is emitted from Earth’s surface. Some of this heat is then reflected back to Earth. If the greenhouse gases were not present, all of the heat would
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