Midterm Notes

Midterm Notes - Midterm 1 Notes I. 1.1 Our Place in Space...

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Midterm 1 Notes I. 1.1 Our Place in Space A. Earth is neither central nor special B. Sun – a star near the edge of a huge collection of stars called the Milky Way galaxy C. Giant stars died in huge explosions scattering the elements (hydrogen, oxygen, carbon, and many more) 1. Matter collected into clouds of gas that slowly collapsed to make new star D. Sun and its plants are nearly five billion years old E. Universe – totality of all space, time, matter, and energy F. Astronomy – study of the universe G. Light year – distance traveled by light in a year 1. About 300,000 kilometers/second 2. Equal to about 6 trillion miles/year II. 1.2 Scientific Theory and the Scientific Method A. Theory – the framework of ideas and assumptions used to explain some set of observations and make predictions about the real world – must be continually tested 1. Used to construct a theoretical model of a physical object or phenomenon that accounts for its known properties a) Model makes further predictions about the object’s properties b) If experiments/observations favor those predictions further developed and refined c) If don’t favor must be reformulated or rejected B. Scientific theory – combining thinking and doing – theory and experiment 1. Testable – separates science from divine revelations
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Midterm 1 Notes 2. Continually tested and their consequences tested also 3. Simple – most successful theories tend to be the simplest ones that fit the facts a) Occam’s razor – If two competing theories both explain the facts and make the same predictions, then the simpler one is better. 4. Elegant – naturally ties together and explains several phenomena previously thought to be completely distinct C. Untestable theories rarely gain any measure of acceptance in scientific circles D. Gravity is only a theory, but calculations based on it have guided human spacecraft throughout the solar system E. Birth of modern science – Renaissance (late 14 th to mid-17 th century) 1. First documented uses of the scientific method by Aristotle (384-322 B.C.) a) Best known ideas were based on pure thought, with no attempt at experimental test or verification b) Thought Earth must be round c) Predicted that any and all future lunar eclipses would show Earth’s shadow to be curved, regardless of our orientation F. Hypothesis – one possible explanation of the observed facts 1. One or more “well-tested” hypotheses may be elevated to the stature of a physical law and come to form the basis of a theory of even broader applicability III. 1.3 The “Obvious” View A. Can see about 3,000 points of light with unaided eye 1. Human tendency to see patterns and relationships among objects even with no real connection a) Different cultures often made the same basic B. Constellations – named after mythological beings, heroes, and animals 1. Some served as navigational guides a) Polaris indicates north
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Midterm 1 Notes 2. Served as primitive calendars to predict planting and harvesting seasons
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This note was uploaded on 06/26/2009 for the course ASTR 50810 taught by Professor Rhodesjr during the Fall '08 term at USC.

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Midterm Notes - Midterm 1 Notes I. 1.1 Our Place in Space...

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