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Lunar and Planetary Science XXXIII (2002) 2007.pdf STARS AND PLANETS: A NEW SET OF MIDDLE SCHOOL ACTIVITIES. M. L. Urquhart, NASA Ames (MS 239-20, NASA ARC, Moffett Field, CA 95054, [email protected]) Introduction: Astronomical and Planetary Science concepts of size, distance, and time can be very difficult for students to understand [1]. Scale Model Solar System activities are commonly used at levels ranging elementary [1] to college [2] for the purpose of helping students visualize their “place in space”. Star and Planets (for grades 6-8) expands upon the idea of a Scale Model Solar System to include the sizes and distance of stars and the life cycle of stars, while introducing students to areas of exciting and current research such as the search for extrasolar planets. Each activity in the set is a math as well as a science activity and has been developed with attention to the Benchmarks for Science Literacy [3] and the Principles and Standards for School Mathematics [4]. Stars and Planets is designed to be presented as a unit, with each new activity building upon concepts presented in previous lessons. However, each hands-on, inquiry-based lesson plan in the set can also be done as a stand-alone activity to allow for better integration into existing curricula. Background information is provided for both educators and their students, as is a Things to Think About section to help facilitate follow-up discussions in the classroom. Scale Model Solar System: In this exercise (based on the Colorado Model Solar System on the Campus of the University of Colorado at Boulder), students create their own scale model solar systems from common materials for the purpose of exploring concepts of size and distance in the solar system. The scale factor is 1 to 10 billion, on which scale the Sun is the size of a grapefruit and the Earth is the size of a candy sprinkle. Key concept include: • All planets are much smaller than the Sun. • The Earth is a relatively small planet. • The solar system is mainly empty space. • The scale of the solar system is immense. • The small inner planets are much closer to the Sun than are the outer planets. Sizes of Stars: Students model the sizes of main sequence stars with every day objects using the same scale as the Scale Model Solar System activity. They then compare the sizes of stars of different classes (on this scale ranging from the size of a cherry to a small car) to the Sun and Earth. Key concepts include: • Stars are not all the same. They come in different colors, sizes, and masses. • The Sun is a medium sized star. • The Earth is much smaller than any star. Distances of Stars: Using maps, students plan a scale model to explore the distances between stars, focusing on Alpha Centauri, the system of stars nearest to the Sun. This activity builds upon the activity Sizes of Stars, and once again uses a scale factor of 1 to 10 billion. Key concepts include: • Distances between stars are immense compared with the sizes of stars • The planets are much closer to the Sun than the next closest star Star Birth: Students learn about the birth of stars in interstellar clouds of gas and dust. This activity differs from the previous lessons in the set in that it does not involve scale models. Rather, students use a hands-on exercise in probability to learn about the relative number of stars of different classes (masses) that are born in a typical stellar nursery. An Internet extension is also provided in which students compare and contrast images of different stellar nurseries imaged by the Hubble Space Telescope. Key concepts include: • Stars are different ages. • Stars are born in giant clouds of gas and dust • Many more low mass (cool) stars are born than high mass (hot) stars. Lifetimes of Stars: In this activity, students return to the concept of a scale model. For Lifetimes of Stars, however, students make a scale model of time rather than distance, and compare Lunar and Planetary Science XXXIII (2002) 2007.pdf Stars and Planets: M. L. Urquhart the lifetimes of different masses of stars to each other and to the geologic timeline for the Earth. Students then make predictions about what classes of main sequence stars might have planets with interesting (as defined by the students) life forms, assuming the history of life on Earth is typical. Key concepts include: • How long a star shines is very dependent on its mass • Low mass stars have less hydrogen to convert to helium than do high mass stars, but live much longer • Our sun has lived about half of its life as a main sequence star. • For most of the history of the Earth (and the Sun), bacteria and other microorganisms were the only form of life on our planet. • The lifetimes of stars are relevant to the search for life on planets outside our solar system Death of Stars: Each of the previous activities on the topic of stars dealt with stars on the Main Sequence. In Death of Stars, students once again use a scale factor of 1 to 10 billion. Working individually of in small groups, students determine the scaled sizes of exotic objects such as red giants, white dwarfs, and black holes. They then compare the sizes of dying stars and stellar remnants to the scaled sizes of the Sun, Earth, distances in the Scale Model Solar System, and a Main Sequence M class (red) star from the previous activities. Key concepts include: • Dying stars can be much bigger than main sequence stars. • The objects left behind when a star dies (a white dwarf, neutron star, or black hole) are the size of the Earth or smaller. • Our sun will never go supernova. Searching for Planets beyond the Solar System: The final activity in Stars and Planets brings together the concepts presented in the unit in an investigation of the challenges astronomers face in the ongoing search for extrasolar planets. (A quote from the activity: “Trying to see the Earth from Alpha Centauri would be like trying to see a candy sprinkle on a donut in New York when you are standing in L.A.”) Students are introduced to current ground-based efforts as well as proposed missions such as Terrestrial Planet Finder[5]. Key concepts include: • Planets shine by reflecting light from their parent star. • Stars are much brighter than planets. • Planets can be detected without being “seen”. • Earth-like planets are much harder to find than Jupiter-like planets. Educator Partner/Primary Field Test Site: Stars and Planets is currently undergoing field testing on a volunteer basis. The main field test site is the classroom of educator partner Marg Freeman, an 8th grade Physical Science and Astronomy teacher at Lewis and Clark Middle School in Meridian, Idaho. Additional field testers are welcome! Availability: Field test versions of each lesson plan in Stars and Planets are available, along with other space science and physics materials on the author’s education Web site at: http://lyra.colorado.edu/sbo/mary/. Acknowledgments: Many of the activities in Stars and Planets were inspired by my time as a laboratory instructor in graduate school at the University of Colorado at Boulder. The Scale Model Solar System activity is based upon a laboratory exercise for the Colorado Model Solar System [2], as are portions of the Sizes of Stars and Distances of Stars activities. I also appreciate the helpful comments and suggestions from educators such as Sheri Klug, Marg Freeman, and Sally Urquhart. My education Web site is available thanks to the generosity of Sommers-Bausch Observatory. References: [1]Fraknoi, A. ed. (1995) The Universe at Your Fingertips, Astronomical Society of the Pacific. [2] Gleason, K. (1997) The Colorado Scale Model Solar System in the Introduction to Astronomy Lab Manual, CU Boulder. [3]AAAS Project 2061, available on line at http://www.project2061.org/tools/benchol/bolframe.htm [4] Full text is available online form the National Council of Teachers of Mathematics at http://standards.nctm.org/ [5] http://tpf.jpl.nasa.gov/