Making a Tennis Ball Globe

Making a Tennis Ball Globe

U. S. DEPARTMENT OF THE INTERIOR U. S. GEOLOGICAL SURVEY

Make your own Earth and Tectonic Globes By Tau Rho Alpha*, Scott W. Starratt* and Cecily C. Chang1 Open - File Report 93-380-A

Description

This activity contains instructions and two patterns for making a terrestrial globe and a tectonic globe. The pattern or map projection is designed to be glued onto a used tennis ball. The terrestrial globe is intended to help visualize the location of the continents and oceans. The purpose of the tectonic globe is to help visualize the location of the Earth's plates and types of plate boundaries (e.g., spreading, convergent, and transform). By constructing and examining the globes, students and others will obtain a greater appreciation of why the edges of continents are located where they are, and of the shape and position of the Earth's plates and their boundaries. This exercise will give the students an insight as to how the parts of Earth's surface are put together. Included in this report are the paper patterns (map projections), instructions for assembly, educator's guides, and a simple description of terrestrial and tectonic globes.

Educator's Guide

 A globe is a world map on the surface of a small sphere that represents the Earth. Of all the world maps, the globe is the easiest to understand because it gives us the most realistic picture of the Earth and has the same attributes as the Earth; round and immense, and impossible to see all at once. Spatial attributes such as distance, direction, shape, and area are preserved as well as the continuity of the all-curved surface. Globes represent the best possible map projection because they include a minimum of distortion and are the ultimate in geographic realism. Globes come in all sizes and are designed for many uses. Most are terrestrial or geographic globes, some are for decoration, without much thought given to geography as we know it, and some are training globes for navigation and general education. Globes that represent the heavens are called celestial globes. Today's globes are constructed of plastic, but, before plastic was available, paper and plaster were used. Early globes used handdrawn segments of a map projection that were attached to a sphere. These segments, called gores, were tied together near the equator and separated or interrupted toward the poles. As most printing machines cannot print on the all-curved surface of a sphere, the gore method of making globes is still used. 

Tennis ball globes Two globes can be constructed using the enclosed world maps. Each of the world maps is composed of twelve gores that are designed to be attached to a tennis ball. Each gore has a width of 30°, the time it takes the sun to travel two hours over the surface of the Earth. The twelve gores can be cut into four groups of three gores each and glued onto the tennis ball, or the gores can be glued on as a group of twelve. Either way, it is important to have the equator divide the tennis ball into two equal parts and for the equator to be in a straight line. See instructions for the construction of tennis ball globes, pages 9 and 10 in this report.