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Climate ChangeEntry Lesson Planetary Temperatures Activity

SC.912.E.7.7 Identify, analyze, and relate the internal (Earth system) and external (astronomical) conditions that contribute to global climate change.

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Essential Questions

• What factors determine the

average temperature of a

planet?

• In what ways can you describe

how the earth is heated?

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0.svg

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Extension Question

How can you relateo internal (planetary system)

– and o external (astronomical)

conditions of Earth’s global

climate change to at least 1 of the

other inner planets?

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http://wardssciencewiki.wikispaces.com/file/view/composite_earth1_red.gif/162969781/composite_earth1_red.gif

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Electromagnetic Spectrum• Photons: packets of energy

o Have no mass

o Can travel through space

o Travel along wave paths

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cuss/72057594124976565/

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Radiation can be reflected, scattered, or absorbed

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http://www.eco-info.net/what-are-greenhouse-gases.html/reflection

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Planetary Temperature

• How does the average temperature of a planet depend on

its distance from the sun?

• Simple model Input: From the sun

Output: Radiation of a heated object

• Analysis Equilibrium: Input = Output

D=distance from sun, T=average temperature

Create a combination of D & T that is a constant

Use data to see how close each planet is to the same constant.

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Design a Model to Simulate Solar Radiation

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Collect DataModel Planet

NameDistance

from Heat Source cm

Equilibrium Temperature

Degrees Celsius

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Input• Let S=total power (energy produced/time) of the sun (S ~

4x1026 watts)

• This power passes through the surfaces of all spheres of

that orbit the sun with radius R centered at the sun.

• The surface area of a sphere =4πR2.

• Power/Area = Intensity = S/4πR2

• Note: Same “inverse square law” applies to gravitational

attraction, spatial variation of sound and light intensity.

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Input Intensity = S/4πR2

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Output

• Radiation of heat from the object

• Common approximation: treat the planet as a “black

body”: Intensity = aT4

T: temperature (measured from absolute zero)

A: constant

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Solar Input & Radiative Output

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Equilibrium: Solar Input=Radiative Output

• S/4πR2 = aT4

• (S/4πa) = R2T4

• Model Prediction: RT2 = constant (all R).

• Test prediction: Measure R and T for various planets and note

whether the prediction is valid.

• Create a bar graph showing RT2 for each planet

PREDICTIONS?????(C) Copyright 2014 - all rights reserved www.cpalms.org

Predict temperatures for planets

Planet Name Average Distance from Sun

Astronomical Units

Average Temperature

Degrees Kelvin

Mercury .39 400

Venus

Earth

Mars

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Inner Planet DataPlanet Name Average

Distance from Sun

Astronomical Units

Average Temperature

Degrees Kelvin

Mercury .39 400

Venus .72 730

Earth 1.00 280

Mars 1.52 213

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Excel Model•  

Mercury

Venus

Earth Mars

0

50000

100000

150000

200000

250000

300000

350000

400000

450000

1 2 3 4

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1. What determined the temperature of your planets?

2. Did your planets come to an equilibrium temperature? What is happening at that temperature?

3. If your sun got hotter, would the temperature change? How?

4. If your planet got farther away, would the temperature change? How?

5. What conclusion can you draw when analyzing your model data and the actual measurements for the inner planets?

Closure: Planetary Temperatures

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Inner Planets

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http://evansscienceblog.blogspot.com/2012/02/inner-planets.html