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• Thales


  First known person to use natural explanations for natural phenomena rather than turning to supernatural world
• Thales

  • He believed that "everything comes out of water and that EARTH FLOATS ON WATER
• Anaximander


  Refined the ideas of Thales
• Anaximander


  • He proposed that "a cylindrical Earth is at rest in the center of the universe, surrounded by air, and by one or more spherical shells with holes in them"
• Anaximenes


  • Suggested that the stars were fixed onto a solid transparent crystalline sphere that rotated about the Earth
• Anaxagoras


  • Stated that the moon shine by reflected sunlight had mountains and was inhabited and the sun was not a GOD but a large fiery stone much larger than Greece and a large distance from Earth
• Democritus


  • Proposed that the Milky way was composed of thousands of unresolved stars
  • Atoms
• Empedocles


  • He said that light travelled fast but not at infinite speed
  • Four universal elements
• Pythagoras


  • One of the first to use mathematics to challenge question and support his observations of the stars
  • He and his followers believed in a well-ordered harmonious universe based on geometry rather than experiments
  • Pythagorean theorem
  • Field of expertise - Mathematics and Astronomy
• Plato


  • He viewed the universe as perfect and unchanging
  • He reasoned that the most perfect orbit of a planet would be circular and its motion is constant like the stars
  • The universe was also described as a large spherical ball with the stars all at the edge and the Earth in the center
  • "Saving the appearance" – EMPEDOCLES MOTIONS
• Ptolemy


  Geocentric Theory - an astronomical model in which the Earth is considered as the center of the universe
• Nicolaus Copernicus


  Heliocentric Theory - an astronomical model in which the Earth and planets revolve around the sun at the center of the universe

  
• DIURNAL MOTION


  Apparent daily motion of the sky from east to west in which celestial objects are seen to RISE and SET
• ANNUAL MOTION


  Carries the sun eastward in the sky over the course of an entire year. It brings in new constellation as the year progresses

  
• Constellations


  A group of stars that appears to form a pattern or picture
• RETROGRADE MOTION OF THE PLANETS (Retrograde Motion)

  1. Planets do not only move relative to the fixed stars but they change direction, generally moving from west to east

  2. The truth behind the motions of heavenly objects must be circular motion at a constant speed which forever remains the same
• 24 hours does it take the Earth to complete a single rotation
• Hipparchus


  • Noted that the position of the stars were shifted in a systematic way which indicated that they were not the ones moving but the Earth
  • Equinox - greatest contribution of Hipparchus in the motion of the universe
• Precession


  • The motion of Earth which consists of a cyclic wobbling in the Earth's axis of rotation with a period of 25, 772 years
  • The slow movement of the axis of a spinning body around another axis due to a torque (such as gravitational influence) acting to change the direction of the first axis. It is seen in the circle slowly traced out by the pole of a spinning gyroscope
• Equinox/Equinoxes


  • The ecliptic and the celestial equator intersect at two points
  • The time or date (twice each year) at which the sun crosses the celestial equator, when day and night are of approximately equal length (about September 22 and March 20)
  • Leap Year (366 days) - a calendar year that contains an additional day compared to a common year

  
• Aristotle


  • He believed that motion itself had certain properties. And rest is the natural state of the universe because most things we see are not moving
• TWO TYPES OF MOTION

  • CELESTIAL MOTION – As an unchanging endless circular motion of heavenly objects in a sphere
  • TERRESTRIAL MOTION – Pertains to movement of matter that has been classified: Alternation or Alternate motion, Natural or vertical motion, Horizontal or violent motion
• Plato: '"Success is determined not by the completion of some action, but by how one engages in all action with wisdom and intelligence"'