There are five three-dimensional Platonic solids. The faces of a Platonic solid are identical regular polygons and all vertex angles are equal. These solids are:
As illustrated in the accompanying transparency, Kepler spent most of his life assuming that planetary orbits were circular and trying to use Platonic solids to deduce their radii. Only much later, after he gave up his dream, did he discover his true laws for planetary motion. Although Kepler's original dream was a failure, much of the same mathematical/geometrical spirit prevails in our modern attempts to explain the fundamental nature of matter via symmetry, group theory, field theory, the geometry of various higher dimensional manifolds, and string theory.
						Illustrate the globe						Read More
					
						Demonstrate how the radius of the earth can be measured using trigonometry.
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						Illustrate how a crater forms as a result of an impact or a blast from below.
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						Mass driver and ring heater show coronal holes and coronal heating.
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						Demonstrate how nuclei attract each other if they come close enough together.
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						Show how sunspots are darker than their surroundings due to lower temperatures.
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						Show the relationship between the phases of the moon and the relative earth-sun-moon positions.						Read More
					
						Illustrates shadow umbra and penumbra						Read More
					
						Show umbra and penumbra with an extended source, as in an eclipse.
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						Identify the source of penumbra regions.
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						Illustrate the approximate angular disposition of the planets around the sun.
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						Illustrate the epicycle nature of Ptolemy's model of the solar system
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						Demonstrate the observation of another planet as seen from the earth.
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						Demonstrate the sun-earth-moon spatial relationship and related concepts..
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						Illustrate the relative sizes of the planets						Read More
					
						Demonstrates how density stratification (differentiation) in interior of planets occurs.
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						Visualize the Platonic solids and Kepler's dream for using them to explain planetary orbits.
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						Illustrate some relationships between the earth, the sun, and certain heavenly bodies
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						Show how a telescope can view any point in the sky using a universal mount.
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						Show the apparent motion of the night sky.
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						Illustrate the orbital motion of a binary star system.
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						Show how we view a rotating binary star.
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						Illustrate the orbits of stars in an eclipsing binary.
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						Show how air currents cause the "twinkling" of a star.
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						Illustrate why a planet does not "twinkle" like a star.
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						Show the changing field pattern from a rotating dipole.
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						Illustrate beaming pattern of pulsars and pulsed binary X-ray sources.
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						Model gravitational collapse.
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						Provides models for hydrogen burning to produce helium in stars via the proton-proton chain.
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						Shows how rays are focused by a standard reflecting telescope.						Read More
					
						Illustrate our galaxy.
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						Show that "permanent" spiral structure can exist as a wave which moves independently from the fluid
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						Demonstrate the concept of the expansion of the universe.
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