The vastness of the solar system offers a unique lesson in large numbers and in scale. THE SCHOOLYARD SOLAR SYSTEM was developed to demonstrate the solar system to scale; to show the relationship between units of thousands, millions, and billions; and to accomplish these goals with student involvement that will re-enforce the lessons.

The Sun and the nine planets are represented on a set of web pages. Each contains information on an object's true and scaled size and on its distance from the Sun. A dot represents the body's scaled size. (Printers and monitors vary, the dots may not appear at exactly the size stated.) There are two models. The first is designed for a 100 foot (30 meter) space. At this scale only the planets Jupiter through Neptune are at least one pixel in size. The other model is designed for a larger space, and has Saturn out at 330 feet (100 meters), Jupiter at 180 feet (55 meters), and Pluto at 1360 feet (414 meters). While showing the full solar system at this scale may not be practical due to space limitations, it is the minimum size that shows all the planets at a size of at least one pixel. If a space this large is not available at your school, then part of the solar system, to Mars or Jupiter for example, may be laid out. Each model is given in U.S. units (miles, feet, and inches) and metric units (kilometers, meters, and centimeters).

Using THE SCHOOLYARD SOLAR SYSTEM pages is easy. First, print out the pages, or cards, for the Sun and each planet. Then lay out the distance on an unobstructed area such as a playground or sporting field. Choose a student volunteer to represent the Sun, and to hold up the Sun card at the origin. Next give out the planet cards, Mercury, Venus, Earth, and Mars, and have each pupil hold their card at the correct scaled distance from the Sun (see the image above). Demonstrate the difference in scale between the size of the dots representing the planet diameters and their distances from the Sun. Point out that the true planet diameters are thousands of miles or kilometers, while the distances from the Sun are millions of miles or kilometers. Continue with the outer planets through Pluto. Here is where the enormity of scale becomes evident as the true distances to the Sun exceed a billion miles or kilometers. The individual pages on the Web can also be used to study the planets without printing them out. Clicking on the planet images will give larger version of the image.

When the solar system is laid out to scale ask some of the students who are not holding a card to visit a planet and tell about its size and distance from the Sun. Ask the remaining students to visit a planet and say whether they can see any other planet's scaled dots from their location. Back in the classroom give a lesson on numbers in the thousands, millions, and billions, using the planet sizes and distances as examples.

Click on the appropriate planet to see that planet's page:

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Planetary Fact Sheets** - More detailed information about the planets

Author/Curator:

Dr. David R. Williams, dave.williams@nasa.gov

NSSDC, Mail Code 690.1

NASA Goddard Space Flight Center

Greenbelt, MD 20771

+1-301-286-1258

Original Version: December 1995, DRW

Last Updated: 20 January 2005, DRW