## Sun's Impact on Earth's Temperature Student Instruction and Answer Sheet

 Materials Needed On-Line Planet Temperature Model Digital Images of Venus (1) (2) and (caption) Digital Images of Earth (1) and (animated) Digital Images of Mars (1 & caption) (2 & caption) and (QT movie) Today's Earth Weather Today's Mars Weather (image and source) Useful On-line Resources On-Line Planet_Temperature Model Solar System Collaboratory WorldWatcher software Today's Earth Weather Today's Mars Weather (image and source) Mars MPG Spring Weather Movie at North Pole Mars Weather QuickTime Movie NASA Hubble Space Telescope Mars Images NASA Photoplanetary Journal
Part I - Observing the Planets
Consider the weather and cloud patterns visible on Venus, Earth, and Mars. Which planet has more chaotic weather patterns?  Propose several possible hypotheses.

 Venus Earth animatedGIF Mars QuickTimeMovie TemperatureRange850 to 900 FRotationalPeriod248 days TemperatureRange-70 to 140 FRotationalPeriod24 hours TemperatureRange-200 to 40 FRotationalPeriod24 hours

Part II - Computer Models
The last time a class conducted the assessment in the section above, they concluded that Venus has more dynamic weather patterns than Earth, which, in turn, has more dynamic weather patterns than Mars. Similarly, they noted that Venus has little variation in temperature, while Earth has a moderate variation in temperature, and Mars has a widely varying temperature. The class settled on three competing hypotheses. Your task is to use the computer models from the Solar System Collaboratory (URL to evaluate which hypothesis seems to be the most correct or to propose your own.

 Pat's Hypothesis The farther away a planet is from the Sun, the colder it is. Chris's Hypothesis A planet far from the Sun can be hot if it has a high albedo. Aaron's Hypothesis A planet far from the Sun can be hot if it has a high greenhouse effect.

INSTRUCTIONS ON HOW TO USE THE SOLAR SYSTEM COLLABORATORY COMPUTER MODELS.
1. Access the Solar System Collaboratory Computer Model (image and real-time access)
2. Notice that the model contains an imaginary planet, Planet X. Wherever you click the mouse, Planet X will move to that point.  Try moving it around and see what happens to the temperature gauge on the right side of the screen.
3. Read the temperature gauge as accurately as you can and CONVERT the Kelven temperature to Fahrenheit by entering a number in the KELVIN BOX and clicking in the FAHRENHEIT BOX.  It is useful to remember that 300 K is about room temperature, 70 F.
4. Change the characteristics of Planet X above the temperature converter.  You can:
1. observe the planet's temperature as it relates to distance;
2. change the planet's albedo (reflectivity) of the atmosphere in a range of values from 0 to 1;
3. change the planet's atmospheric composition, called the GREENHOUSE EFFECTIVENESS) in the range of 0 to 1000.  To learn more about the Greenhouse Effectiveness, you might want to check out this on-line resource.
5. To get a feel for the numbers, start by putting Planet X at the same distance Earth is from the Sun and start changing the variables of albedo and greenhouse effectivenss to see what happens to the temperature.  Can you make Earth have a temperature of 75 F?

EVALUATING THE HYPOTHESES

Consider each of the hypothese proposed below and test each one using the Collaboratory Computer Model.  Analyze the strengths and weaknesses of each proposal and decide which is the most correct.  Or better yet, propose your own hypothesis and provide data to support your proposal.

 Pat's Hypothesis The farther away a planet is from the Sun, the colder it is. Chris's Hypothesis A planet far from the Sun can be hot if it has a high albedo. Aaron's Hypothesis A planet far from the Sun can be hot if it has a high greenhouse effect. Your Hypothesis Your Hypothesis  Your Hypothesis  Your Hypothesis

Part III - Asking More Questions of the Computer Models
1. How does varying the planet's distance from the Sun change the temperature?  If you double the distance, does it halve the temperature?  If you triple the distance, does the temperature drop to 3-2 (that is,one ninth) its original value?
2. How good is the model?  Can you replicate the listed temperature on Mercury, Venus, Earth, and Mars?
3. How does changing the albedo change a planet's temperature?  Why does this occur?
4. How close do you need to move Mars in order for it to sustain life?  How far away do you need to put Venus?  Can you make these planets sustain life?

 FFS - Facts for Students The sun is the major source of energy for phenomena on the earth's surface, such as growth of plants, winds, ocean currents, and the water cycle.  Seasons result from variations in the amount of the sun's energy hitting the surface, due to the tilt of the earth's rotation on its axis and the length of the day.
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