The Scale of the Cosmos
Zoom outward in steps of 100
•It has taken twelve steps of 100 to go from human scale to the scale of the cosmos
•Remember the gap when moving outside our solar system
•How do we conveniently deal with this large of a range of sizes?
•Use different units for different types of scales  (i.e. km, AU, light-years)
•But hard to compare, hard to do calculations
•Use scientific notation (and metric “prefixes”)
17,000 ly
1,700,000 ly
170,000,000 ly