Chapter 8: Section 1 - The Size and Scale of the Universe

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In this section you will find materials that support the implementation of EarthComm, Section 1: The Size and Scale of the Universe.

Learning Outcomes

  • Develop a scale model of the solar system.
  • Evaluate different scale models and compare their strengths and limitations.
  • Use mathematics to calculate distances to objects in the universe in astronomical units (au), light-years, and parsecs (pc).

Using Technology

To learn more about the distances in space, complete the following:

Distances between Stars and Galaxies

  1. Astronomers use sky maps to map the stars and describe their locations. You will use a software program called Google Earth to explore a sky map. Using a computer with an internet connection, open Google Earth. If your computer does not have Google Earth installed, go to to download a free version.
    Google Earth
  2. Click the icon on the toolbar to choose Sky. You will see a view of the sky from your location on the Earth. White dots represent stars on the sky map.
  3. Using the Google Earth navigation controls, locate 10 stars on the sky map. Click on the white dot for each star to retrieve descriptive information about the star.
    1.  Create a table that lists the name and distance of each star.
    2.  What are the closest and farthest stars you located? How do their distances compare to the distance of Proxima Centauri? How do they compare to the distance of the Andromeda Galaxy?

Inquiring Further

  1. To learn more about solar-system walks, visit the following web sites:

    Build a Solar System Walk, Exploratorium
    Make a scale model of the Solar System and learn the REAL definition of "space."

    Voyage: A Journey Through the Solar System along the National Mall in Washington DC, National Center for Earth and Space Science Education
    Planning a visit to the nation's capital? If so, check out the scale model of the solar system along the National Mall. For more information, read this article about the exhibit in Smithsonian magazine.
  2. To learn more about the five stars nearest to the Sun, visit the following web sites:

    The Nearest Star, NASA
    Learn how far Proxima Centauri is from Earth, as well as how astronomers calculate distances to stars.

    The 26 Nearest Stars to Earth, University of Wisconsin
    Examine a list of the closest stars to Earth.

    The Nearest Stars: a Guided Tour, The Astronomical Society
    A tour through the stellar neighbourhood.


To learn more about this topic, visit the following web sites:

Astronomical Unit (AU), Near Earth Object Program, NASA
Find out more about the Astronomical Unit.

What is a light year and how is it used? Starchild, NASA
This description is similar to the text in EarthComm but also offers links to other relevant pages.

If a Millimeter Were a Year/Light-Year, Kelley L. Ross
Comprehending a distance as great as a light year is difficult. This brief essay puts the light-year in perspective by comparing it to a millimeter.

The Cosmic Distance Scale, NASA
This resource gives an impression of how immense our Universe is by starting with an image of the Earth and then zooming out to the furthest visible reaches of our Universe.

Animations and Video

To view animations and video related to this topic, visit the following web sites:

Milky Way, NASA
Take an interactive tour of the Milky Way (Flash needed).

Launchpad: New Horizons Covers the Distance, NASA
Locate and watch the NASA eClip titled, “Launchpad: New Horizons Covers the Distance.” This video explains how scientists use astronomical units to measure large distances in space.