Issues in Earth Science 

“Eww, There’s Some Geology in my Fiction!”

Issue 1, June 2014


Teacher Resources

Suggestions for Activities and Discussions to accompany a Reading of

 Diversion Program by Robert Dawson.

Diversion Program provides a starting place for learning about the motion of bodies in our solar system, gravity, and the scale of distances in space—all learning goals of the Next Generation Science Standards (2013) and the National Science Education Standards (1996).  Below we offer a few classroom discussion points and activity suggestions that might accompany Diversion Program to either kick off or tie up a classroom unit.


Phases and Terminators

Classroom activities developed to teach lunar phases often call for modeling the motion of the Earth and Moon relative to the Sun.  In a similar way, students can develop models for the motion of Grendel and Beowulf.  Students might use a small potato to represent Grendel and draw on the potato with a black marker to shade the dark side of the asteroid that faces away from the Sun.  The terminator is then represented by the boundary between normal and blackened parts of the potato-turned-asteroid (although shading a dark side does not allow students to see how the terminator moves across the surface of the asteroid as the asteroid rotates). Students might also sketch out on paper what Grendel looks like as seen from the Beowulf at different positions in orbit around Grendel.  For additional spatial visualization, students could sketch what both Grendel and the Beowulf look like at those same positions, if viewed from a distant fixed location.


Questions to pursue with your students:

1.  Explain why it would take 90 minutes for the cycle of phases. 

2.  Which body goes around which?

3. If someone was standing on Grendel, say at the terminator, where would the Sun and Beowulf appear in the sky if Grendel was at full phase as seen from the Beowulf?  Where would Sun and Beowulf appear in the sky if you were at “midday” on Grendel and the phase was first or third quarter as seen from the Beowulf?

4.  How does the terminator move relative to the ground on Grendel?  Relative to the Beowulf in orbit around Grendel?

5.  Artists often use some artistic license in interpreting their subject.  The illustration for Diversion Program shown below looks like it could represent the moment when the rest of the crew spots Zig’s artwork on Grendel’s surface at the end of the story (notice the dark number 17 in the picture).  However, the picture doesn’t quite match this moment.  Using your understanding of phases, explain why not.

Image credit:  Erin Colson

Other resources for phases and terminators

1.  A dandy classroom-ready activity on phases can be found in the TOPS book: The Earth, Moon and Sun, Lesson 13.  This resource is available for purchase and download at a modest price.

2. Want more information or details?  Feel free to e-mail us with questions or comments at Dr.C “at” earthscienceissues “dot” com---or post questions on our Q/A blog at


Modeling Phases and Thinking in 3D – an application to the Earth-Moon-Sun system


The study of the motion of the bodies in space is a great place to introduce the concept of modeling.  If students develop, use, and understand models of the rotation and revolution of Earth and Moon, they can explain or predict all kinds of Earth-based observations.  Models for motion can explain observations that at first seem unrelated, like eclipses, the Sun’s rising in the east, the apparent motion of the Sun across the sky, the wheeling of stars overhead at night, and the seemingly odd times of day or night when you see the different phases of the Moon in the sky.


A student-friendly interactive animation of the phases of the Earth’s moon is available at

Image credit:  Astronomy Education at the University of Nebraska in Lincoln

Students can experiment with what the Moon phase looks like at different positions in the Moon’s orbit and see where in the sky the Moon appears at different times of day and different phases of the Moon.  Teachers might discuss with students what aspect of lunar phases each figure on the animation is designed to show--for example the view called Horizon Diagram shows the Moon and Sun’s position in the sky, but not the distance between the Moon and the Sun.



Small Diversions

What are the two “small diversions” in the story that produce big changes?  Reflect on the effect of small changes in science and in life (cause and effect).


How can the tiny effect of light pressure possibly move the asteroid enough to miss Earth? How can a very small diversion several years out change the path of the asteroid enough?


Think about two straight paths that go at slightly different angles.  To start with, the paths stay very close together.  But as they go farther and farther from the starting point, they diverge significantly.  Grendel will travel hundreds of millions of miles before it encounters Earth, so a very small diversion causes a big difference in where it is at the moment it crosses Earth’s orbit in 23 years.   Consider the simplified conceptual illustration of paths shown below, remembering that both the asteroid and the Earth are moving (Earth orbits the Sun many times as the asteroid approaches, and, although it is not specified in the story, Grendel also might orbit the Sun several times during that 23 years).

Image credit:  Russ Colson.  Sun and Earth images courtesy of NASA

You can watch a You Tube video of a near miss of an asteroid in 2012 here.

Additional videos of the near-miss asteroid D14 are shown on this NASA site.

For the truly dedicated, you can simulate your own asteroid misses at



Thinking in Math

1. At one point in the story, Zig comments that they have reached 100.002% of target coverage of the asteroid.

a. Is more than 100% possible?  What if the report was 100.002% coverage rather than 100.002% of target coverage?

b. In what other situations might greater than 100% not be possible?  For example, if someone reported that a rock was made of 100.002% SiO2, is that possible?  Sometimes scientists report concentrations greater than 100%, but this is related to uncertainties in measurement.  What does uncertainty mean?  Feel free to post thoughts on teaching uncertainty on our blog that addresses that issue:  uncertainty-in-science.

2. Zig mentions in the story that his speed in orbiting Grendel is not “fast enough to earn us a speeding ticket in a school zone.”

Your students can calculate his speed given how long it takes to orbit the asteroid, the size of the asteroid, and the Beowulf’s distance above the surface.  They will need to know the relationship between diameter and circumference of a circle, and the idea that velocity is a distance traveled divided by the time to travel that distance.

3. In the story, it takes four minutes for a message to go from the Beowulf to Earth and another four minutes for an answer to return from Earth. 

Based on the speed of light in vacuum, 186000 miles per second, how far is the Beowulf from Earth?


Connecting to the Next Generation Science Standards

Diversion Program provides a launching place for exploring motion of bodies in space and helps students to imagine a “real” context where phases are important.  A full classroom unit might include the Next Generation Science Standards (NGSS) Performance Expectations listed below.  Relevant National Science Education Standards (NSES) from 1996 are also listed as well as example Practices of Science and Cross Cutting Relationships from the NGSS.

Lesson Topic

NGSS Performance Expectations

NGSS Science and Engineering Practices*

NGSS Cross Cutting Concepts


1. Motion of bodies in space, phases and eclipses.


MS-ESS1-1.  Develop and use a model of the Earth-sun-moon system to describe the cyclic patterns of lunar phases, eclipses of the sun and moon, and seasons.

Develop and use models to describe phenomena.


Develop and use a model to predict phenomena.

Patterns can be used to identify cause and effect relationships.

Earth and Space Science: Earth in the solar system, grades 5-8.

2. Scaling the distances between objects in space


MS-ESS1-3 Analyze and interpret data to determine scale properties of objects in the solar system.


Analyze and interpret data to determine similarities and differences in findings.

Time, space, and energy phenomena can be observed a various scales using models to study systems that are too large or too small.

Use mathematics in all aspects of scientific inquiry, 5-8

3. Gravity


MS-ESS1-2 Develop and use a model to describe the role of gravity in the motions within galaxies and the solar systems.


MS-PS2-4 Construct and present arguments using evidence to support the claim that gravitational interactions are attractive and depend on the masses of interacting objects.


HS-ESS1-4 Use mathematical or computational representations to predict the motion of orbiting objects in the solar system.


Develop and use a model to describe a phenomenon.




Construct and present oral and written arguments supported by empirical evidence and scientific reasoning to support or refute an explanation or a model for a phenomenon.


Use mathematical or computational representations of phenomena to describe explanations.


Models can be used to represent systems and their interactions.




Models can be used to represent systems and their interactions-such as inputs, processes, and outputs-and energy and matter flows within systems.




Algebraic thinking is used to examine scientific data and predict the effect of a change in one variable on another.

Earth and Space Science: Earth in the solar system, 5-8.


Physical science: motions and forces, 9-12

4. Newton’s laws of motion


MS-PS2-1 Apply Newton’s Third Law to design a solution to a problem involving the motion of two colliding objects.



HS-ESS1-4 Use mathematical or computational representations to predict the motion of orbiting objects in the solar system.

Apply scientific ideas or principles to design an object, tool, process or system.




Use mathematical or computational representations of phenomena to describe explanations.

Models can be used to represent systems and their interactions-such as inputs, processes, and outputs-and energy and matter flows within systems.


Algebraic thinking is used to examine scientific data and predict the effect of a change in one variable on another.

Physical science:  motions and forces, 9-12

* Students should encounter the practices in each topic of study in the science classroom.  Students should not encounter just one practice for a particular topic, but several practices at once.  For example, students can construct explanations (practice 6) for phases (of Moon, of Grendel or any other body in space) based on the models the students developed (practice 2).  See Appendix F of the NGSS for more information on the science and engineering practices.


Other Teaching Tidbits

1. Although optical phenomena are not specifically called out in the NGSS, you might talk with your students about the glory seen by the characters in the story.  A glory results from a combination of reflection, refraction, and diffraction of light. Glories can sometimes be seen around the shadow of your own head when you are high in the mountains and your shadow falls onto clouds below you (tiny droplets of water in the clouds acting like the beads in Diversion Program).  You can sometimes see a glory around the shadow of an airplane you are riding in if the airplane’s shadow falls on lower clouds.


a. You might ask students what the orientation of the Sun, Grendel, and Beowulf has to be for the glory to be visible.

b. A picture of a glory can be seen at Earth Science Picture of the Day for Dec 30 2011.


2. Other words in the story that your students might ask about include solar wind, electrostatic charge, retroreflective, light pressure, and carbonaceous asteroid.


a. The solar wind is made of particles streaming out from the sun at high speed.  Although we call this “wind”, the particles are very far apart in the vacuum of space.  Protons are the most common particles.  The charged protons, and their interaction with rock, can produce an electrical charge in small particles on the surface, like the beads in the story.


b. Retroreflective is more than just reflective.  A retroreflective surface reflects light back directly from the direction it came from.  This amplifies the effect of light pressure in diverting the asteroid because the light is reflecting back all in the same direction, rather than some of it being reflected one way and some another.


c. Carbonaceous chondrites contain more carbon and water than most other meteorites/asteroids, but they are still mostly silicate (rocky) material.  This group of meteorites/asteroids is considered primitive in that they have not been part of a planetesimal and been separated into iron-rich and rocky parts.  They contain minerals like olivine, clay-like minerals, and magnetite, along with organic molecules such as amino acids—the building blocks of life.

You might ask your students to look up the differences among asteroids, meteorites, and meteors and then talk about those differences.  What is an asteroid?  What kind of object is it? What is it made of? What does carbonaceous mean?


3. Students often think that there is no gravity in space.  You might ask them what makes the Beowulf go around Grendel rather than continue in a straight line.  What does “free fall” mean?


4.  Action-reaction and Newton’s laws of motion can be addressed through the following segment of the story:


“Nice work, Major!” said Golubova. She put her hand on his right shoulder and clapped him on the left, bracing so as not to put them both into a spin.


Why did she need to brace herself, and, based on Newton’s laws of motion, how would they have each spun if she hadn’t braced herself—in the same direction or different directions?



The Teacher Resources for Diversion Program are written by Russ and Mary Colson


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