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Published byMelvin McKenzie Modified over 6 years ago

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History of Astronomy Motions of the sky caused by and controlled by gods. Big Horn Medicine Wheel Temple at Caracol

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Greek Astronomy - 600 BC Science - “to learn” Thales - the world is logical/understandable. Stars are “balls of fire.” Predicted solar eclipse.

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Pythagoreans Math is the language of music; language of science Perfect triangle - divine number. Pythagorean Theorem Round earth & moon

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Classical Greece - 450-300 BC Socrates (470-399 BC) Plato (430-350 BC) Aristotle (384-322 BC) Alexander the Great Democritus Aristotl e

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Helenistic Era:350 BC - 400 AD Alexandria - intellectual hub of the world. Aristarchus (310-230 BC) - earth orbits the sun

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Erastosthenes Circumference of Earth (276-200 BC)

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Ptolemy - Geocentric Universe 127-145 AD Deferents & Epicycles Retrograde Motion Almagest - “Greatest of All Books”

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Geocentric Universe Earth at center Spheres for each planet (Mercury, Venus, Mars, Jupiter & Saturn); Moon, Sun, Zodiac constellations, stars.

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Retrograde Motion

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Hipparchus (190-120 BC) Catalog stars Calculate lunar month Precession of equinoxes

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Europe - The Dark Ages Calendars didn’t work! Mercury and Venus were different. Occam’s Razor Calendars didn’t work! Mercury and Venus were different. Occam’s Razor

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The Copernican Revolution Nicolas Copernicus 1473 - 1543; Poland Canon in church; Calendar reform Heliocentric model “On Revolutions” Nicolas Copernicus 1473 - 1543; Poland Canon in church; Calendar reform Heliocentric model “On Revolutions”

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Explanations of Retrograde Motion Ptolemaic Copernican Epicycles & Deferents Inner Planets move faster Ptolemaic Copernican Epicycles & Deferents Inner Planets move faster

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Tycho Brahe (1546 - 1601) Great naked-eye observer Supernova of 1572 Comet - outside of atmosphere Uraniborg observatory Prague & Kepler Great naked-eye observer Supernova of 1572 Comet - outside of atmosphere Uraniborg observatory Prague & Kepler

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My Tycho

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Johannes Kepler (1571 - 1630) Tycho’s assistant - 1600 Determine the orbit of Mars Astrology Three Laws of Planetary Motion Tycho’s assistant - 1600 Determine the orbit of Mars Astrology Three Laws of Planetary Motion

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1 st Law of Planetary Motion The orbits of planets are ellipses with the sun at one focus. 1.Semi-major axis - Astronomical Unit 2.Eccentricity; e = c/a The orbits of planets are ellipses with the sun at one focus. 1.Semi-major axis - Astronomical Unit 2.Eccentricity; e = c/a

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2 nd Law of Planetary Motion Planets travel faster at perihelion, slower at aphelion; but sweep out equal areas of space in equal amounts of time.

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3 rd Law of Planetary Motion The square of a planet’s orbital period is proportional to its semi-major axis cubed. k = P 2 /R 3 Period is in Earth years Radius is in AU k = 1 P 2 = R 3 The square of a planet’s orbital period is proportional to its semi-major axis cubed. k = P 2 /R 3 Period is in Earth years Radius is in AU k = 1 P 2 = R 3

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Galileo Galilei (1564 - 1642) 1609 - Telescope 1.Venus 2.Sun 3.Moon 4.Jupiter 5.Saturn 1610 - Published 1632 “Dialogue Concerning the Two Chief World Systems” House Arrest

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Telescope; diagrams of planets

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Sunspots; Jupiter’s Moons

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Isaac Newton (1642 - 1727) Born Christmas Day Cambridge; closed for plague Age 23-24; 18 mos. invented calculus Optics Laws of Motion, Law of Universal Gravitation Explained Kepler’s Laws “Principia”

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Newton’s Laws of Motion First Law: Every body continues in a state of rest or in a state of motion in a straight line unless it is compelled to change that state by a force acting on it. Second Law: When a force F acts on a body of mass m, it produces and acceleration a equal to the force divided by the mass.Thus, a=F/m, or F=ma. Third Law; To every action there is an equal and opposite reaction.

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Gravitation Every particle of matter in the universe attracts every other particle with a force that is directly proportional to the product of the masses of the particles and inversely proportional to the square of the distance between them.

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