1. The History of Astronomy http://www.phys.uu.nl/~vgent/babylon/babybibl_intro.htm http://mason.gmu.edu/~jmartin6/howe/Images/pythagoras.jpg http://www.russellcottrell.com/greek/aristarchus.htm http://www.mesopotamia.co.uk/astronomer/homemain.html plato.lib.umn.edu/ http://web.hao.ucar.edu/public/education/sp/images/aristotle.html http://web.hao.ucar.edu/public/education/sp/images/ptolemy.html http://www.windows.ucar.edu/tour/link=/people/ancient_epoch/hipparchus.html http://copernicus.atspace.com/ http://www.danskekonger.dk/biografi/andre/brahe.htm/ http://antwrp.gsfc.nasa.gov/apod/ap960831.html http://www.lucidcafe.com/library/95dec/newton.html

12. Stonehenge 0

14. Other Examples All Over the World Big Horn Medicine Wheel (Wyoming)

18. Caracol (Maya culture, approx. A.D. 1000) Contained window that were aligned with rising point of Venus over the horizon

20. Passage of astronomical knowledge Ancient Babylon Ancient Egypt Ancient Greece Ancient Roman Empire

22. Mesopotamia/Babylon Modern political boundaries Ancient Babylon

24. Karnak

25. Giza

27. Ancient Greece

30. Eratosthenes’s Experiment

31. D. Ptolemy Believed the Earth was the center of the universe Believed the sun and planets circle the earth.

33. Ptolemy’s Idea of the Universe Earth is in the center. Planets circle the earth. Sun orbits the Earth .

35. http://www.er.uqam.ca/nobel/r14310/Ptolemy/Images/Regiomontanus/1496.g.jpg The Almagest

36. IV. Rome The Romans most important contribution to the field of astronomy is the enforcement of a systematic calendar that would account for fact that the year is about ¼ of a day more 365 days. The astronomers of Julius Caesar convinced him to create the Julian Calendar which adds one day to the calendar every 4 years to account for the time we had skipped. This is known as a “leap year”.

37. Ancient Rome

38. 3. The Renaissance 1300’s-1500’s

40. Heliocentric Universe

42. Let’s put the Earth on an Epicycle

43. It’s still pretty tricky Ptolemy Copernicus

45. Let’s put the Earth on an Epicycle

48. Uraniborg : Castle of the Heavens

49. Tycho Brahe observing the supernova in 1572. www.tayabeixo.org/articulos/tycho.htm

50. Tyco Brahe’s Universe Earth does not move & Lots of Circles

55. Observed Phases of Venus * Galileo Found the Gibbons phase of Venus, which proofed that Venus orbited the Sun

57. Ellipse Focus #1: Planets orbit the Sun in elliptical paths with the Sun at one focus

58. 4. The Modern age

65. History of Astronomy The sphere of the sky surrounds the Earth and is called the “celestial sphere.” Back

66. History of Astronomy The two constellations Leo, (A), and Cygnus, (B), with figures sketched in to help you visualize the animals they represent. (Photo (A) from Roger Ressmeyer, digitally enhanced by Jon Alpert. Photo (B) courtesy Eugene Lauria.) Back

67. History of Astronomy The Sun hides from our view stars that lie beyond it. As we move around the Sun, those stars become visible, and the ones previously seen are hidden. Thus the constellations change with the seasons. Back

68. History of Astronomy The Earth's rotation axis is tilted by 23.5° with respect to its orbit. The direction of the tilt remains the same as the Earth moves around the Sun. Thus for part of the year the Sun lies north of the celestial equator, whereas for another part it lies south of the celestial equator. Back

69. History of Astronomy These five diagrams show the Sun's position as the sky changes with the seasons. Although the Earth moves around the Sun, it looks to us on the Earth as if the Sun moves around us. Notice that because the Earth's spin axis is tilted, the Sun is north of the celestial equator half of the year (late March to late September) and south of the celestial equator for the other half of the year (late September to late March). Back

70. History of Astronomy The direction of the rising and setting Sun changes throughout the year. At the equinoxes the rising and setting points are due east and west. The sunrise direction shifts slowly northeast from March to the summer solstice, whereupon it shifts back, reaching due east at the autumn equinox. The sunrise direction continues moving southeast until the winter solstice. The sunset point similarly shifts north and south. Sunrise on the summer solstice at Stonehenge. (Courtesy English Heritage.) Back

71. History of Astronomy (A) The cycle of the phases of the Moon from new to full and back again. (B) The Moon's phases are caused by our seeing different amounts of its illuminated surface. The pictures in the dark squares show how the Moon looks to us on Earth. Back

72. History of Astronomy A solar eclipse occurs when the Moon passes between the Sun and the Earth so that the Moon's shadow strikes the Earth. The photo inset shows what the eclipse looks like from Earth. (Photo courtesy of Dennis di Cicco.) Back

73. History of Astronomy A lunar eclipse occurs when the Earth passes between the Sun and Moon, causing the Earth's shadow to fall on the Moon. Some sunlight leaks through the Earth's atmosphere casting a deep reddish light on the Moon. The photo inset shows what the eclipse looks like from Earth. (Photo courtesy of Dennis di Cicco.) Back

74. History of Astronomy (A) During a lunar eclipse, we see that the Earth's shadow on the Moon is curved. Thus the Earth must be round. (B) As a traveler moves from north to south on the Earth, the stars that are visible change. Some disappear below the northern horizon, whereas others, previously hidden, become visible above the southern horizon. This variation would not occur on a flat Earth. Back

75. History of Astronomy Eratosthenes's calculation of the circumference of the Earth. The Sun is directly overhead on the summer solstice at Syene, in southern Egypt. On that same day, Eratosthenes found the Sun to be 7° from the vertical in Alexandria, in northern Egypt. Eratosthenes deduced that the angle between two verticals placed in northern and southern Egypt must be 7°. Back

76. History of Astronomy Aristarchus used the size of the Earth's shadow on the Moon during a lunar eclipse to estimate the relative size of the Earth and Moon. Back

77. History of Astronomy How to determine linear size from angular size. Back

78. History of Astronomy Aristarchus estimated the relative distance of the Sun and Moon by observing the angle A between the Sun and the Moon when the the Moon is exactly half lit. Angle B must be 90° for the Moon to be half lit. Knowing the Angle A, he could then set the scale of the triangle and thus the relative lengths of the sides. Back

79. History of Astronomy Motion of the Earth around the Sun causes stellar parallax. Because the stars are so remote, this is too small to be seen by the naked eye. Thus the ancient Greeks incorrectly deduced that the Sun could not be the center of the Solar System. Back

80. History of Astronomy Cutaway view of the geocentric model of the Solar System according to Eudoxus. (Some spheres omitted for clarity.) Back