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Astronomy

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Astronomy

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    1. Astronomy The study of the motion of the heavens.

    4. The Big Horn Medicine Wheel: Located in the Big Horn Mountains about 45 miles west of Sheridan, Wyoming, this is a sacred site to many Plains tribes, including the Absaroke, Blackfoot, Lakota, and Cheyenne; it is made of stones and is approximately 70 feet in diameter.

    5. The Greeks: Observations Give Rise to . Science

    7. OK, if we are on a spherical Earth ….. How Can We Know How Big It Is?

    11. Pythagorean Universe time: about 550 bc first recorded attempt at rational explanation of heavens formed foundation for Greek astronomy

    12. Philosophical Ideas The heavens represent perfection. The circle is the perfect shape. All heavenly motions must be circular.

    13. Pythagorean Model stars reside on stellar sphere stellar sphere rotates about axis in 23 hours 56 minutes Sun follows path called ecliptic going once around in one year accounts for most observations!!

    25. Ptolemy’s Epicycles

    26. Ptolemy’s Epicycles

    27. Ptolemy’s Epicycles

    28. Ptolemy’s Epicycles

    29. Ptolemy’s Epicycles

    30. Ptolemy’s Epicycles

    31. Ptolemy’s Epicycles

    32. Ptolemy’s Epicycles

    33. Ptolemy’s Epicycles

    34. Ptolemy’s Epicycles

    35. Ptolemy’s Epicycles

    36. Ptolemy’s Epicycles

    37. Ptolemy’s Epicycles

    38. Ptolemy’s Epicycles

    39. Ptolemy’s Epicycles

    40. Ptolemy’s Epicycles

    41. Ptolemy’s Epicycles

    42. Ptolemy’s Epicycles

    43. Ptolemy’s Epicycles

    44. Ptolemy’s Epicycles

    45. Ptolemy’s Epicycles

    46. Ptolemy’s Epicycles

    47. Ptolemy’s Epicycles

    48. Ptolemy’s Epicycles

    49. Ptolemy’s Epicycles

    50. Ptolemy to the Renaissance Ptolemy’s work kept alive by Arab astronomers last major incarnation in 13th c DOMINATED FOR NEARLY 1500 YEARS!

    52. The Copernican Model heliocentric (sun-centered) stars are very far away Earth rotates on axis Earth revolves around Sun

    53. Old model Copernicus did not like.Old model Copernicus did not like.

    59. Epicycles? Problem: Copernicus still could not predict the planet’s positions accurately with circular orbits. Solution: Re-introduce epicycles! Question: Is this any simpler?

    60. Tycho Brahe (1546-1601) born just after publication of Copernicus’ work (1543) world’s best naked-eye astronomer created an enormous catalog of exact planetary positions night after night Danish Nobleman a bit of an eccentric fellow!!

    62. Tycho’s Work built first modern observatory amassed records of planetary positions from 1576 to 1591 observations were 2.5 times more accurate than any previous records devised his own model of the Universe

    65. Data Driven Models used Tycho’s library of observational data let observational records (data) dictate the orbits instead of philosophy found non-circular orbits planets out of orbital plane A planet’s speed depends on distance

    68. Orbital Eccentricity

    69. What is the shape of Earth’s orbit around the Sun? Earth, e = 0.017

    78. THIRD LAW The size of the orbit determines the period of revolution planets that orbit near the Sun orbit faster than planets that are far from the Sun

    80. Review One of the consequences of Kepler’s third law is that Jupiter takes longer to orbit the Sun than does the Earth. planets near the Sun take longer to go once around the Sun. Earth is moving faster when close to the Sun.

    83. The hammer and the feather

    95. Newton observed: all objects fall at the same rate near the Earth orbital motion is just high speed falling

    98. LAW OF GRAVITY Describes mathematically how the strength of gravitational attraction depends on mass and separation.

    99. HUGE POINT: Newton was able to start with the law of gravity and show that Kepler’s laws were an inevitable consequence! The physics dictates the orbits!!!!!

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