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Discover Magazine: How Big is My Universe?
Teacher’s Guide
Grade Level: 6-8
Curriculum Focus: Astronomy/Space
Lesson Duration: Two class periods
Program Description
What better way to answer the eternal question about size than to bring the solar system down to
Earth? Astronomer Sheldon Schafer did just that by converting Peoria, Illinois, and its immediate
surroundings into a scale model of our solar system. Join Schafer as he bikes from one planet to
another to gauge the vastness of distances in outer space.
Onscreen Questions and Activities
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Pre-viewing questions
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What do you know about the sizes of the planets in our solar system?
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What do you know about the distances between the planets?
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As you watch the program, note how astronomer Sheldon Schafer overcame the
obstacles of size and distance with his model, and judge for yourself how well the
model works.
Post-viewing questions
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Because we can’t see the whole solar system at one time, we have to rely on models
to get a complete view of it. Discuss the difficulties in creating a scale model of the
solar system.
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Can you think of other things that we can see completely only by relying on models?
Activity: Choose three planets and estimate how long it would take to reach them at the speed
of light. Poll the class and record their results on a chart. Then find the actual distances and see
how close the estimates came.
Lesson Plan
Student Objectives
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Review Earth’s place in the universe.
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Understand the speed of light and the concept of light-years.
Discover Magazine: How Big is My Universe?: Teacher’s Guide
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Create a “time machine telescope ” that shows images of objects within and outside the solar
system; explain how long it takes light to travel from each one.
Materials
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Discover Magazine: How Big is My Universe?
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Computers with Internet access
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Access to color printers
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Index cards
Procedures
1. After watching the program, ask students to explain what astronomer Sheldon Shafer meant
when he said, “Our solar system is just a doorstep to the universe.” As a class, review Earth’s
place in the universe. For example:
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Earth and the other planets revolve around a star called the sun. Together, the sun
and stars make up the solar system.
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The sun is just one of 100–200 billion stars in our Milky Way galaxy.
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The Milky Way galaxy is one of 2,000 galaxies in of the Local Group of galaxies.
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The Local Group of galaxies is part of the Virgo Supercluster of galaxies.
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Clusters of superclusters of galaxies make up the universe.
2. Discuss the speed of light. How fast does light travel? Why is this speed important in physics?
(Light travels at 186,000 miles per second. According to modern physics, it is the fastest thing in the
universe.) In the video, the astronomer talked about riding his bike “at the speed of light,” but he
was only going 6 to 7 miles per hour. How could this be? (He was riding at the speed of light given
the scale model of the solar system, in which 42 feet equals about a million miles.)
3. Ask students to think about how the speed of light relates to objects we see in space. Even given
such speed, it still takes light time to reach us on Earth. Give the following examples:
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The moon is Earth’s closest object in space, about 240,000 miles away. It takes the
light from the moon 1.3 seconds to reach Earth. That means when we look at the
moon, we see what it looked like 1.3 seconds ago.
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The sun is 93 million miles away. It takes light rays from the sun about 8 minutes to
reach Earth, so we see the sun as it looked 8 minutes ago.
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The planet Saturn is about 10 times farther away than the sun. When we see Saturn
through a telescope, we see what it looked like 80 minutes ago.
4. Explain that even though these distances are very great, they’re really quite small compared to
the distances between objects outside the solar system. For example, the nearest star, Proxima
Centauri, is so far away that it takes 4.2 years for its light to reach Earth. When astronomers
describe distances and size outside our solar system, they use a new unit of measurement called
Published by Discovery Education. © 2005. All rights reserved.
Discover Magazine: How Big is My Universe?: Teacher’s Guide
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a light-year. Ask students to define a light-year. (The distance light travels in one year.) So Proxima
Centauri is 4.2 light-years from Earth. Ask students to figure out individually or with a partner
the approximate distance in miles of a light-year:
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Light travels 186,000 miles per second.
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There are 60 seconds in a minute, 60 minutes in an hour, 24 hours in a day, and 365
days in a year. Multiply these together to get 31,500,000 seconds in a year.
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Multiply that times 186,000 miles per second and you get 5,850,000,000,000 miles, or
about 6 trillion miles.
5. To help students understand how and why light-years are used to describe distances in
astronomy, share the following example: Our Milky Way galaxy is about 100,000 light-years
across. Why would astronomers describe this distance in light-years rather than miles?
6. Tell students that the farthest objects ever seen in space are galaxies called “Hubble Deep
Field.” Astronomers estimate these galaxies are billions of light-years away. In fact, they say
that they offer a glimpse of what the universe looked like when it was first forming. How could
that be? (Help students understand that we’re seeing these galaxies as they looked billions of
years ago, which is why they offer what can be considered a look back in time.)
7. Next, share the following Web site with students and have them click through images under
“Telescope as Time Machine”:
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Discovery School: Understanding the Universe: Light-Years
http://school.discovery.com/schooladventures/universe/itsawesome/lightyears/index.html
8. Tell the class that they will create a “time machine telescope.” Divide the class into small groups
and have each group find two images to “view” through the telescope: One object inside the
solar system, and the second outside. For each object, students should print a color image and
write the following information on an index card:
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The name of the object
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The distance from the Earth
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The time it takes the light from this object to reach Earth
9. Students will find an array of images and information on the Web. The following Web sites
provide a good starting point:
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The Nine Planets (scroll down each planet page for links to images)
http://www.nineplanets.org/
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Hubble Site: Gallery (spectacular images from Hubble Space Telescope)
http://hubblesite.org/gallery/
10. Have students hang their telescope images and accompanying index cards on the board.
Assessment
Use the following three-point rubric to evaluate students’ work during this lesson.
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Discover Magazine: How Big is My Universe?: Teacher’s Guide
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3 points: Students showed a strong understanding of Earth’s place in the universe and the
concepts of the speed of light and light-years; correctly calculated the distance of a light-year;
identified two appropriate images for the “time machine telescope,” and provided complete
and correct information for each object.
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2 points: Students showed a satisfactory understanding of Earth’s place in the universe and the
concepts of the speed of light and light-years; provided mostly accurate calculations for the
distance of a light-year; identified two appropriate images for the “time machine telescope,”
and provided complete information for each object, although there were mathematic errors.
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1 point: Students showed a weak understanding of Earth’s place in the universe and the
concepts of the speed of light and light-years; did not correctly calculate the distance of a lightyear; did not identify two appropriate images for the “time machine telescope,” and or
information provided was incomplete or inaccurate.
Vocabulary
galaxy
Definition: A group of stars, usually numbering in the billions, that orbit a common mass and
travel through the universe as a single unit; our galaxy is called the Milky Way.
Context: Our sun is one of 100 to 200 billion stars in our Milky Way galaxy.
light-year
Definition: The distance light travels in one year; about six trillion miles
Context: Astronomers use light-years to describe the vast distances in the universe.
planet
Definition: A low-mass body that orbits a star
Context: Jupiter is big enough to hold all the planets and their moons.
solar system
Definition: The planets and bodies that orbit the sun and any group comprising a central star
and orbiting planets
Context: Astronomer Sheldon Schafer has converted the entire city of Peoria and its immediate
surroundings into a scale model of the solar system.
Academic Standards
Mid-continent Research for Education and Learning (McREL)
McREL's Content Knowledge: A Compendium of Standards and Benchmarks for K-12 Education
addresses 14 content areas. To view the standards and benchmarks, visit
http://www.mcrel.org/compendium/browse.asp.
This lesson plan addresses the following national standards:
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Discover Magazine: How Big is My Universe?: Teacher’s Guide
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Science—Space Science: Understands the composition and structure of the universe and the
Earth's place in it.
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Mathematics: Understands and applies basic and advanced properties of the concepts of
measurement.
National Academy of Sciences
The National Academy of Sciences provides guidelines for teaching science in grades K-12 to promote
scientific literacy. To view the standards, visit this Web site:
http://books.nap.edu/html/nses/html/overview.html#content.
This lesson plan addresses the following national standards:
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Earth and Space Science: Earth in the Solar System.
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Physical Science: Transfer of energy.
The National Council of Teachers of Mathematics (NCTM)
NCTM has developed national guidelines for teaching mathematics. To view the standards online, go
to http://standards.nctm.org/.
This lesson plan addresses the following math standards:
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Number and Operations: Understand numbers, ways of representing numbers,
relationships among numbers, and number systems.
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Measurement: Apply appropriate techniques, tools, and formulas to determine
measurements.
Support Materials
Develop custom worksheets, educational puzzles, online quizzes, and more with the free teaching tools
offered on the Discoveryschool.com Web site. Create and print support materials, or save them to a
Custom Classroom account for future use. To learn more, visit
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http://school.discovery.com/teachingtools/teachingtools.html
Published by Discovery Education. © 2005. All rights reserved.