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• Cosmology


  The study of the origin, evolution, and fate of the universe
• Democritus


  Held that all matter is consisted of tiny particles that were so small that they could not be broken down into any smaller pieces. Coined the word 'atomos' which literally means invisible.
• Democritus's view of atoms


  • Atoms of water were smooth because water flowed and had no discernible shape
  • Atoms of fire were thorny which is why the fire gave you painful burns
  • Atoms of earth were rough and jagged so that they stuck together to form hard materials
• Empedocles


  Combined the ideas of Thales, Anaximenes, and Heraclitus, and added the element of Earth. Thus, was born the notion of all matter being made out of differing amounts of fire, air, earth and water.
• Aristotelian physics pertains to the terrestrial realm. About 400 B.C. he definitively established the four classical elements of fire, air, earth and water, which were acted on by two forces, gravity and levity.
• Aristotle later added a fifth element, ether, to describe the void that fills the universe above the terrestrial sphere.
• Natural motion of earthly objects


  1. Straight lines toward center of Earth

  2. Bodies in motion naturally tend to come to rest

  3. Applied force causes deviation from natural motion

  4. Continuous application of force is needed to sustain any motion other than natural motion
• Types of terrestrial motion


  • Motion with respect to quality
  • Motion with respect to quantity
  • Motion with respect to place
• Celestial motion


  Perpetual, no reason for these motions to happen, the constant motion of celestial objects is natural
• Diurnal motion


  The apparent daily motion of stars and other celestial bodies around the Earth, caused by the Earth's rotation on its axis
• Annual motion


  The apparent motion which is a reflection of the Earth's annual orbit around the Sun
• Precession of the Equinoxes


  A cyclic wobbling in the orientation of Earth's axis of rotation, currently about 50.3 seconds of arc per year or 1 degree every 71.6 years, takes 25,772 years for a full precession to occur
• Precession is caused by the gravitational source of the sun and the moon, and the fact that the Earth is a spheroid and not a perfect sphere
• Evidence that the Earth is spherical


  • Traveler's tales of ships disappearing over the horizon
  • The Pole Star shifting to a higher position in the sky as one journeyed north
  • Aristotle's observations that there were stars seen in Egypt and in Cyprus which were not seen in the northerly regions
  • The Earth's shadow is always circular during a lunar eclipse
  • The Pole Star is higher in the sky even in short travels northwards
• Aristarchus and Eratosthenes actually measured the size of the Earth