Rotation and Flattening LessonOverviewAs we observe the thousands of galaxies in the visible universe, we find that many of them are flattened disks. Because the process of galaxy formation is too slow to watch, scientists study it with computational models. This lesson/activity demonstrates how one might explain the appearance of so many flat galaxies with a computational model.Preparation and MaterialsThe teacher should be familiar with the GalaxSee application (for those unfamiliar with this software, there is an online tutorial), have it loaded on a PowerMac, and have some means of displaying the monitor to the class.ObjectivesStudents will
StandardsThis lesson fulfills portions of the following standards and curriculum guidelines:
Activities
Note: As the stars clump to the center, their speeds will increase rapidly, and error will start to accumulate in the model. If this is allowed to continue, the model will become unrealistic, and could, for example, throw all of the stars out beyond the original boundaries. This is an inaccurate result, and if you allow the simulation to run beyond the initial clumping, you should be sure to discuss the implications of error in the model. For more information about detecting and controlling error, see the section about the info window in the GalaxSee tutorial.
Discussion of the SimulationAsk the students to discuss the differences between the two simulations. Ask them if they can think of other situations in which rotation flattens things. (Like hand-tossed pizza crust, spinning a Koosh® ball or key ring, for example).Discussion of ObservationAsk the students to look at what they wrote about the two simulations. Tell them to suppose that they were the first people in the world to discover that rotating galaxies flatten over time. Is what they wrote adequate to explain this new discovery to the public or to other scientists? What would they need to include in or change about their writing in order to make it useful and clear to another person? Are they sure that they understand the relationship? Should they do more or different tests? Have them critique their own writing from this standpoint, and discuss what they learned from this.Assign them to write a clear and accurate report of what they observed. Emphasize that it is important that they know what software was used, and what parameters were set. Be sure to go through the setup procedure again so that they can record this information. CollaborationAfter they have polished their reports, instruct them to prepare and post a note to WebCaMILE for another group of students to see. If possible, have the other group of students attempt to repeat the experiment as described in the note, verify the findings of the first group, and provide feedback about their methods and conclusions. Encourage both groups to ask questions of each other's procedure and observations. If another group of students is not available, you could split one class into two large groups and require them to communicate only through writing.ExtensionsFurther ExperimentationHave the students use GalaxSee to try different values for the rotation, number of stars, dark matter, distributions, etc, observing and recording the effects.For example, have each student create a different galaxy, iterate it, and record the experiment (including initial conditions). Then have the students exchange reports with one another, and attempt to repeat each others' experiments, comparing and reporting on the similarities or differences of the results. Thinking HarderAsk the students how they would verify the conjecture that flattening in galaxies may be a result of spinning. One way to do this is to see if the flat galaxies we observe in nature are spinning (they are, and this is observable with photometric tools attached to telescopes). However, not all of the galaxies that we observe are flat. What would we expect to find if we observed them to see if they were spinning? How might what we find from these observations cause us to modify our conjecture?Go to GalaxSee Curriculum Resources Please direct questions and comments about this page to WebMaster@shodor.org © Copyright 1996 The Shodor Education Foundation, Inc. |