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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. Ptolemys Epicycles

    26. Ptolemys Epicycles

    27. Ptolemys Epicycles

    28. Ptolemys Epicycles

    29. Ptolemys Epicycles

    30. Ptolemys Epicycles

    31. Ptolemys Epicycles

    32. Ptolemys Epicycles

    33. Ptolemys Epicycles

    34. Ptolemys Epicycles

    35. Ptolemys Epicycles

    36. Ptolemys Epicycles

    37. Ptolemys Epicycles

    38. Ptolemys Epicycles

    39. Ptolemys Epicycles

    40. Ptolemys Epicycles

    41. Ptolemys Epicycles

    42. Ptolemys Epicycles

    43. Ptolemys Epicycles

    44. Ptolemys Epicycles

    45. Ptolemys Epicycles

    46. Ptolemys Epicycles

    47. Ptolemys Epicycles

    48. Ptolemys Epicycles

    49. Ptolemys Epicycles

    50. Ptolemy to the Renaissance Ptolemys 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 planets 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) worlds best naked-eye astronomer created an enormous catalog of exact planetary positions night after night Danish Nobleman a bit of an eccentric fellow!!

    62. Tychos 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 Tychos library of observational data let observational records (data) dictate the orbits instead of philosophy found non-circular orbits planets out of orbital plane A planets speed depends on distance

    68. Orbital Eccentricity

    69. What is the shape of Earths 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 Keplers 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 Keplers laws were an inevitable consequence! The physics dictates the orbits!!!!!

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