Changing Faces: A Study of Solar and Planetary Rotation Rates
Sun, Earth and Mars
In this middle-school level activity, students work as NASA scientists to make repeated observations of our Sun and the planets to determine their rotation rates. First, students create a playground model of rotation and create representative diagrams. Students then observe NASA images of sunspots to determine the rotation rate of our Sun. In the last phase, students download NASA movies from the Internet and measure rotation rates for objects in the solar system. 

Learner Outcomes
By completing this activity, the learner will:

  • describe a scientific model using diagrams
  • observe successive images of our Sun
  • measure a rotation rate for our Sun
  • download NASA movies from the Internet
  • determine rotation rates for a variety of solar system objects
National Science Education Standards

National Mathematics Education Standards

Materials and Technology

Scientific Background

Teacher Lesson Plans

Activity 1: Formulate explanations regarding the Earth's rotational period by watching satellite movies.

Activity 2: Go outside and have students create a model of a spinning planet to recognize and predict the patterns of rotation.

Activity 3: Develop space and time relationships by determining the rotation rate of a group of students moving together to simulate a spinning circle.

Activity 4: Analyze and evaluate the rotation rate data and create sketches of the spinning/rotating circle of students.

Activity 5: Determine the rotation rate of our Sun by watching sunspots move from one side to the other, or by looking at the sequence of pictures.

Activity 6: NASA science teams create a multimedia report.

Changing Faces Teacher Lesson Plans

Learning Cycle Format
Anticipatory Set

Using a classroom globe of Earth, ask students how long Earth takes to rotate once (24 hrs). Challenge students to explain how they know this. (students may suggest that we have movies of it taken by satellites that prove it.  However,  these movies have only been around for about 5 years.  Before that, it was much more difficult to determine the rotation rate). Be certain students know the definition of rotation. 

Change the focus of the discussion to the rotation of other planets. Ask students to develop and write out a strategy that they could use to determine the rotational rate of a distant planet. 

Go back to Activities.
Exploration - Creating a playground model for rotation


During this outside phase, students are going to create a playground model for rotation by forming a rotating circle. One half of the class will be part of the circle and one half will observe from a distance; then, the groups will switch roles.

Create four different colored construction paper signs and label each with a different object: mountain, lake, crater and city. Place four students even distances apart along the circle and hang the signs around their necks with string (or saftey pin the signs to coats). 
students in a circle Challenge the students in the circle to join hands and to make the circle spin as fast as possible while still keeping its circular shape. It is then the task of the observing students to determine the rotation rate of the circle of students by using a stopwatch and observing through their paper-tube telescopes. It will often help if students work in teams of two so that  the observer can shout START and STOP for the timekeeper. Make multiple measurements and calculate the average rotation rate before switching teams. 

Go back to Activities.

Students should combine the rotation rate results for team one and for team two on the blackboard. The focus of this part of the lesson is on how to determine rotation rates at a distance. First ask students to write down exactly the process they used to measure the rotation rate of the circle using the reference signs. Second, have students create two sketches of the scenario: (1) as viewed from eye level and (2) as viewed from above. See the pictures below as examples. Tell students that they will be using this same observational process to determine the rotation rate of our Sun. 

Go back to Activities.
Concept Introduction
Measuring solar rotation rates

View solar image number 001. Notice the location of these spots on the solar surface. Now look at solar image number 002. Where are the spots now? You should note that on the bottom of each image is a time and date mark. These will be very helpful in determining the rotation rate for our Sun. Solar image number 003 appears on a page with lots of additional solar images. 

Determine the rotation rate of our Sun by watching sunspots move from one side to the other, or by looking at the sequence of pictures. It should be close to 25 days. This is how Galileo determined the solar rotation rate in 1610. An animated image of solar rotation is available too!

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Solar images
solar imagenumber 001
solar imagenumber 002


Concept Application
Studying changing faces in the solar system

Arrange students into 4-member NASA science teams and assign to each team one of the following solar system objects. Teams should create a multi-media report that includes six parts:

  1. What object was studied?
  2. How did you determine its rotation rate?
  3. What was the rotation rate of the object?
  4. How does your answer compare with the answer given in a library book?
  5. What other interesting things did you learn about your solar system object?
  6. How successful was your team in completing this task? Provide reasons for your answer.
Go back to Activities.
Selection of Solar System Objects and On-line NASA Resources 
  1. Mars ...{This movie was taken over 96 hours - more information available} ...
  2. Saturn ...{This movie was taken over 9 hours - more information available} ...
  3. Neptune ...{This movie was taken over 64 hours - more information available} ...
  4. Pluto ...{This movie was taken over 24 Earth days - more information available} ...