Models to visualize size and distance in the universe

# HOW FAR IS THAT STAR?

## The Universe: Size and distance proportions made visible

 Here you see 8 different size spheres out of which to construct scale models that will help us visualize sizes and distances in the universe. The model spheres range in size from the smallest, with a diameter of ¼mm, about the size of a grain of fine sand, to the largest, with a diameter of 3.2cm, about the size of a ping pong ball.

Here are some general facts you can use throughout these modeling projects:

 1 mm = 0.001 meter 1 cm = 0.01 meter One yard is approximately one meter One mile = 1600m diameter of a grain of fine sand: ¼mm (see circle A in size diagrams.) number of grains of fine sand in a bucket: 1.25 billion ( or 1.25x109 ) number of stars in an average galaxy: 100 billion number of galaxies in the visible universe: 100-200 billion

Now some more facts, about actual sizes and distances (some are approximate) in the universe:

 1 Light year (distance that light travels in one year) = 1.0x1016m Diameter of the earth = 1.2x107m Diameter of the sun = 1.5x109m Distance from the sun to the earth = 1.5x1011m Diameter of the solar system (twice the distance from sun to Neptune) = 9.6x1012m Distance to Alpha Centauri, the nearest star (other than the sun) = 4.3 Light Years Diameter of the Milky Way galaxy = 100,000 Light Years Distance to Andromeda, the nearest neighboring galaxy = 2,000,000 Light Years

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