The Sun as a Source of Energy



Bruce Zeller

Summer Research Program for Science Teachers

New Rochelle High School

August 2012


Subject: Astronomy

Grades Level: 11 & 12

Time required: 30 minutes for the hands on activity and 20 minutes for the Starry Night computer exercise which is optional

Introduction: In this hand’s on activity students will measure energy from the Sun. They will use Starry Night High School to explore the nature of our daytime star. Upon completion, students will have a better appreciation for the Sun as a star and its influence over life on this planet.


Key concepts:

·         The Sun is the main source of energy in the solar system

·         The Sun’s  Energy comes from the fusion of the lightest element, hydrogen into helium

·         The Sun will continue to shine for another five billion years

Materials required

·         Several glass jars (half liter or half quart size

·         Rubber, cork or foam stoppers for the jars with small central holes in them

·         Thermometers that read at least  20 to 40 degrees celsius

·         Watch or stop watch

·         Graduated cylinder

·         Water

·         Clear sunny day


1.      Fill each jar of about half way with water, insert a thermometer and allow the water to reach room temperature. Record this temperature on

2.      Outside, record the temperature of the water again after about 20 minutes.

3.      View the jar from the same angle that the Sun’s rays were approaching the jar and using a ruler measure the height and width of the “target” presented by the water. (approximate it as a rectangular area)

4.      Pour each jar of water into a graduated cylinder to determine its volume. Record this in table 1

5.      Calculate the energy gained by the Sun by each of the water samples, and the power delivered by the Sun to each bottle.

6.      Calculate the effective area (using the values obtained in step 4) of the water and determine the power per unit area delivered by the sunlight. Compare this figure to the standard average value of 1 kW/m2


Table 1

Bottle        Volume        Mass        Start          Finish        Change         Total      Energy        Power

#               in liters          (kg)           temp.        temp.        temp.            time      gained         (W)


Important formulas needed

1.  1 ml of water has a mass of 1 gram

2. The specific heat of water is 4180 joules/kg-celsius

3. Total energy gained in joules = mass (kg) of water x specific heat x temperature change in C0

4. Power (W) = energy (J) / time (s)


Discussion Questions

1. How much energy did your samples of water absorb from the sunlight?

2. What factors might have affected the amount of energy the water absorbed from the Sun?

3. What results would you expect if you repeated this experiment on Mercury or Mars (assuming that these planets had an atmosphere similar to Earths)?

4. The Sun is a steady source of energy. What might happen to Earth if the Sun was a variable star that changed its energy output with time?


National Standards

Standard A: Science as Inquiry

Standard B: Physical Science

Standard D: Earth and Space Science

Standard E: Science and Technology

Standard F: Science in Personal and Social Perspectives

Standard G: History and Nature of Science


Standard                 Activity to Address the Standard                                             What the Activity Addresses

A                             taking temp and dimensions                                                         skills for scientific inquiry

B                             observing the change in temp                                                       transfer of energy

D                             recording final data                                                                       earth in the solar system – sun in center

E                             calculate energy and power gained by bottle of water                 abilities of technological design like solar panels


 New York Core Curriculum High School

Standard 4

Key Idea 1: The Earth and celestial phenomena can be described by principles of relative motion and perspective

Performance Indicator 1.2

1.2b  Stars form from the gravitational collapse of interstellar gas clouds and are powered by fusion energy