AST 115: Chapter 2
27 Cards in this Set
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What is science?
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science is a rational method of investigation used to discover how nature works
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define a "law" of science
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are not absolute
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are the current best descriptions of nature
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What are 2 important aspects of science
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it is a method of successive approximation
it is self-correcting
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What are the steps in scientific method
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State the problem
perform a relevant experiment
develop a logical way of explaining; theory
test the theory
keep it, or modify, or start over
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What is the most important step in the scientific method?
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testing the theory
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What causes a planet to apparently reverse its motion and then resume it?
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the retrograde motion is an illusion caused by the inner planet catching up and passing an outer, the other planet appears to move westward because of this
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With respect to an inferior planet's orbit viewed from earth, what is greatest eastern/western elongation?
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furthest position eastward or westward in the sky
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With respect to an inferior planet's orbit viewed from earth, what is superior conjunction?
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lined up earth-sun-planet
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With respect to an inferior planet's orbit viewed from earth, what is inferior conjunction?
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lined up: earth-object-sun
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With respect to an superior planet's orbit viewed from earth, what is opposition?
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lined up object-earth-sun
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With respect to an inferior planet's orbit viewed from earth, what is conjunction?
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lined up: earth-sun-object
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How can we get a successful theory?
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Simplicity test
longevity test
scientific test
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What is mundane astrology?
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motion of planets influenced the lives of entire nations
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what is natal astrology?
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individual's life was affected by the arrangement of planets at the moment of ones birth
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What are some arguments against astrology?
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statistical- sheer numbers
cause and effect- what force can explain this
precession- signs of the zodiac change
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What did copernicus do?
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proposed a sun centered solar system, correctly ordered the planets, circular orbits- failed to match ptolemy's accuracy due to elliptical orbits
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What did Tycho Brahe do?
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made non-telescopic measurements of the position of plants over 2 decades, hired kepler to do math
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What did Kepler do?
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interpreted tycho's data and created his 3 laws
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What did Kepler do?
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interpreted tycho's data and created his 3 laws
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What are kepler's 3 laws
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each planet moves in an orbit that is an ellipse with the Sun at one foci
a planet moves faster when closer to the sun
the square of the period is equal to the cube of the semi-major axis of its orbit
P2=a3
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What did Galileo Galile do?
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first telescopic measurements
Venus goes through phases
moon has mountains; suns have spots
jupiter has moons
viewed stars that couldn't be be seen with the naked eye
tower of pisa experiment- acceleration of gravity
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What is the affect of Galileo's observations
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Venus must orbit the sun
heavenly bodies are imperfect
if moons can orbit jupiter, why can't the moon orbit earth
greeks didn't know it all
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What did Sir Isaac Newton do?
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contributed to the ideas of optics, heat, mechanics, astronomy, and calculus
published three laws of motion
an object in rest or motion stats at rest or motion unless acted on by a force
the acceleration of an object is proportional to the force acting on it
for every action there i…
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What is the law of gravity?
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any 2 objects attract each other with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distances between the centers
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What are the three requirements for placing a satellite into orbit
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Gravity of the object it's going to be orbiting
sufficient horizontal velocity
sufficient altitude
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What do astronauts in the space station appear to float?
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gravity is still acting on them, but they are in free fall
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What revisions to kepler's laws did Newton make?
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1st&2nd- conservations of angular momentum= mass x velocity x distance= constant
3rd= (m1+m2)xP2 = a3
m= solar mass
p=earth years
a= AU
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AST 115: Chapter 2