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Nicholas Copurnicus Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Wanderers (Planets ) Inferior Nearer the Sun than the Earth Morning Star/Evening Star Superior Farther from the Sun than the Earth Loops Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Movement of Mars Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Motion of the Sun Moon Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Ptolemy’s explanation Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Glory Years of Astronomy Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Motion of Mars by Copurnicus Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Galileo Galilei Outstanding scientist of his era Bought and built telescopes Observed Venus in gibbous phase moons around Jupiter millions of stars in the Milky Way spots on the Sun craters, highlands and seas on the Moon etc. Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Venus by PtolemyVenus by Copunicus Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Tycho Brahe Invented wonderful observing tools Twenty years of observations Hired Kepler Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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The Solar system by Tycho Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Kepler’s 1 st Law Every Planet revolves around the Sun in an orbit that is an ellipse with the Sun at one focus Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Kepler’s 2 nd Law A line from the planet to the Sun will sweep out equal area in equal time Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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P = a 2 3 Yr AU Kepler’s 3 rd Law The square of the period of a planet is equal to the cube of the semi-major axis Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Sir Isaac Newton Newton was a genius whose work in mathematics, theoretical mechanics and optics completely revolutionized physics Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Gravity F = G Mm r 2 Every object anywhere in the Universe attracts every other object in the Universe by a Force which is proportional to the product of their masses and inversely proportional to the distance separating them. Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Gravity Inverse Square Law The equation for the intensity of light has a similar form to the gravity equation so we can use light to demonstrate the Inverse Square Law. Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Laws of Motion Newton’s 1 st Law A body at rest will remain at rest and a body in motion will remain in motion in a straight line until acted upon by a force. Newton’s 1 st Law In the absence of a force the velocity (V) will not change Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Laws of Motion Newton’s 2nd Law The acceleration of a body is proportional to the force applied and inversely proportional to the mass of the body. Newton’s 2nd Law The change of velocity = acceler- ation (a) = Force / mass F=ma a = F/m Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Laws of Motion Newton’s 3rd Law m 1 v 1 = m 2 v 2 From this law we derive Thrust which makes possible Jet Engines and Rockets For every action there is an equal and opposite reaction Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Orbital Mechanics Knowing that a bullet shot out of gun is pulled to the ground by gravity, Newton envisioned this experiment on the top of the highest mountain. From this experiment Newton related the motion of the Moon to the motion of a falling apple. Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Orbital Mechanics An object is space has a velocity. During a given time the object would move from A to B. But in the same time the gravity from the sun causes it to fall toward the sun the distance from A to D. The resulting trajectory of the object is from A to C. If the object is a planet in orbit we note that the distance from C to the Sun is just the same as the distance A to the Sun. Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Kepler’s 3 rd Law as Modified by Newton Newton discovered while working from ‘first principles’ that Kepler’s 3 rd Law needed to be modified. Leaving out constants… ( M 1 +M 2 ) P = a 23 Masses must be measured in Solar masses, period in Earth years and the distance between masses in Astronomical Units Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Tides Many books explain tides this way. Moon pulls on the water on the Moon side causing it to bulge up a little. The Moon pulls the center of the Earth away from the water on the far side causing it bulge up a little on that side. Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Barycenter Tides ( an alternate explanation) The Earth and the Moon revolve around the common center of mass for the system (Barycenter). The tide one Moon side is due to gravitational force but the tide on the other side is due to centrifugal force. Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com
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Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com The square of the period of a planet is equal to the cube of the semi- major axis is a statement of Kepler’s _____ Law In-Class Quiz
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Chapter 3 Survey of Astronomy twlee2016@gmail.com astro1010-lee.com End Chapter 3
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