This activity combines the concept of Earth’s rock cycle with the characteristics of other planets in the solar system. After learning about Earth’s rock cycle and the basic characteristics of objects in the solar system, students can consider how to extend this concept to other objects. The student’s goal is to create a rock cycle for each selected solar system object.

First as a class, students should agree on a course of action based on their own driving questions. For instance:

• Which objects probably have some sort of rock cycle?

• What information about the object would relate to the rock cycle?

• What are the available resources of information?

• How should we as a class conduct our research and present our results?

After their investigation, students must communicate their results to their peers. This involves not just presentation, but also discussion about the supporting evidence for their rock cycle claims. As an extension, students can investigate the case for Pluto and come up with their own conclusion — what is Pluto?


• StarDate Guide to the Solar System

• Slide projector and slides (optional)



Begin by reviewing the basics of Earth’s rock cycle. Then pose a question about other members of our solar system (not just planets): do they have rock cycles, too? Record students’ driving questions and discuss ways to go about answering those questions. You may wish to reserve Pluto as a special solar system member for later investigation (see the Extend section).


Divide students into small groups of four to six students. Each group should investigate a different planet, depending on the result of the class brainstorm. The StarDate Guide to the Solar System will help students gather information about planetary features that provide clues to the planet’s rock cycle. If students have trouble, help them consider Earth’s rock cycle and how it relates to Earth’s features. Air and water erode rocks into sediments. Earth’s mantle heats buried rocks to make metamorphic rocks. Continents collide and raise mountains for water and air to erode.


The planets closest to the Sun (Mercury, Venus, Earth, and Mars) are rocky; they will most likely show evidence of a rock cycle. The gas giants (Jupiter, Saturn, Uranus, and Neptune) won’t. But these gas giants have rocky moons that can be investigated. For each solar system object, information about its surface features, agents of erosion, and geologic structure under the crust will provide the major clues necessary to construct a possible rock cycle. Check your school’s library for available resources. A wealth of information about the planets resides on NASA’s solar system web sites. One effective way to organize the research is to break the class into research groups, with each focusing on one planet or moon.


Break the students into another set of groups with each member being an expert on a different planet. These groups discuss some of the following questions:

1. What is Pluto? Is it a planet? Why or why not?

2. What about the gas giants — Jupiter, Saturn, Uranus, and Neptune? Instead of rock cycles, might they have gas cycles?

3. Consider what might happen if you could change the conditions on your object, such as adding liquid water to Mars or changing Earth’s atmosphere. Would these changes affect the rock cycles on these bodies?


After their investigation, each group presents its object’s rock cycle to the class. During their presentation students should point to particular features of their planet as evidence that supports different phases of their hypothetical rock cycle. This could be a presentation involving posters or computer graphics. Or it could be something else a bit more interactive, such as a poem or song.

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