Scientific Notation

 Basis of expression for length, size, distance in physical sciences is the meter.

Astronomers deal with big (and little) numbers so they need a system for expressing them. What is the distance to Sun in meters?

149,600,000,000 = 1.496 X 1011meters.

 
Illustration of idea: 14,600 = 14.6 X 1000 = 14.6 X [10 X 10 X 10] = 14.6 X 103 

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Astronomers use scientific notation all the time.

  • Size of Sun and other astronomical objects:
    Earth: radius = 6378 kilometer, diameter = 12756 kilometers.
    Sun: radius = 696,000 kilometers, > 100 times larger.
         Demonstration with basketball and BB for relative sizes.

  • Mass of Sun. Definition of mass; unit = kilogram. 

  •  Its value: kg (good argument for scientific notation).

  • Compare with Earth; kg. Therefore:       First to realize this general idea was Aristarchus of Samos.

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