Scientific Notation

. Basis of expression for length, size, distance in physical sciences is the meter.
Meter stick.
We deal with big (and little) numbers so we need a system. For expressing them. What is distance to Sun in meters?
meters.
Illustration of idea: .
We will use scientific notation all the time in this course.

• 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.
  Transparency with relative sizes of objects.
• Mass of Sun. Definition of mass; unit = kilogram. Question: How could we know this? Its value: kg (good argument for scientific notation).
• I never give numbers for numbers sake; they always tell you something. Compare with Earth; kg. Therefore: . First to realize this general idea was Aristarchus of Samos.
  For freshman, the first thing you learn in college; Earth is a pretty crummy little object.