AST 201S - Stars and Galaxies
University of Toronto Mississauga
Chapter 1 Summary
Essential Cosmic Evolution, 5 Edition th
1. Goals of Chapter 1
• Develop perspective for the course - where are we going?
• Introduce some basic concepts (and skip those not needed)
2. Where are we? (NOTE: questions provide direction)
• Earth (NOTE: not obvious from our every day experience)
• Solar System = Sun, planets and everything else that is part of the Sun’s family
• Milky Way = The Galaxy - containing the Sun and at least 100 billion other
• Universe holds the Milky Way and trillions of other galaxies
• Words like “big” are only descriptive. Must use numbers
• The values of numbers are not important, do not memorize
• How have we learned the numbers?
• What do the numbers tell us?
• What would change if the number changes?
• Numbers are often given as ratios - a comparison of two objects
• Huge/tiny numbers are given in scientiﬁc notation (See Appendix C