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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/