PHYSCI

• Celestial Domain


  The Celestial domain is perfect hence can only be made up of the perfect substance they called "ether" and can only move in perfect motion: circular in path and constant in speed
• Terrestrial Domain


  The terrestrial domain objects are imperfect and that the tendency of things to attain perfection is the cause of their motion. Meanwhile, they also believed that things, depending on their composition of the elements — fire, air, water, and earth — tend to move towards the center of the Universe (center of the Earth) or away from it with earth, naturally, as at the center. Fire and water naturally move away from the center
• Diurnal/ Daily motion of the sky


  The appearance that the objects in the sky moves relative to the Earth's local horizon (celestial objects: moon, Sun, stars, planets; there were only five known planets: Mercury, Venus, Mars, Jupiter, Saturn) as observed for one whole day at the same location on Earth
• Annual motion of the sky


  The appearance that objects in the sky moves relative to the background stars as observed at the same time of the day and at the same location on Earth
• Pythagoras


  • Universe is mathematical; mathematics as the best way to express truth about the Universe; Sun, moon and Earth are spherical; placed Earth as the center of the Universe
• Plato


  • Attainment of perfection as absence of change; celestial spheres being crystalline and contains the moon, the Sun and the stars; explaining the shadows — read on Plato's Allegory of the Cave and the Allegory of the Divided Line — as his description or framework on how to look at the Universe, in particular that the daily and annual patterns of the sky must have a greater reality besides its appearance
• Eudoxus


  • Followed previous models of the universe but added auxiliary spheres to provide appropriate tilt to the planets' path
• Aristotle


  • Two-domain system with terrestrial domain containing four elements that tries to attain perfection by being in their natural location relative to the center of the Universe: the center of the Earth. He was a learner of Plato
• Plato's basic model


  Spherical crystalline shells containing the Sun, Moon, and the five planets (Mercury, Venus, Mars, Jupiter, and Saturn). The stars are fixed in the outermost crystalline sphere that rotates annually
• Eudoxus' model


  • 27 auxiliary spheres are needed to produce the appearance that planets deviate from each other's path. Earth as exact center of the Universe. First to use mathematics
• Aristotle's improved model


  Traced the motion of the celestial objects to a Prime Mover that because of its basic movement, all other crystalline spheres move accordingly. This model requires a geometric and mathematical feat so as to fix the gear ratio of the spheres as well as the correct tilts of their axes relative to each other to produce the same appearance
• Dealing with retrograde motion


  The appearance of the retrograde motion necessitates the addition of more mechanisms called "devices" to produce the visual motion of the planets. Due to complications, the Aristotelian Prime Mover is ignored and instead other philosophers concentrated on the production of retrograde motion of all planets using "devices". Among the devices, one can specifically focus on the combination of deferent and the epicycles
• Ptolemaic system


  Earth is the center, all other celestial bodies orbit the Earth, outermost celestial sphere is fixed
• Copernican system


  Sun is the center, all planets including Earth orbit the Sun, only Moon orbits the Earth, outermost celestial sphere is fixed
• Ursine/Tychonic system


  Earth is the center, the Moon and the Sun orbit the Earth, all other planets orbit the Sun; debatable whether some of orbits (or shells) transect each other; the version of Tycho involves non-crystalline orbital spheres of the planets, outermost celestial sphere is fixed
• The reliability and consistency with the available data are equal for these systems. The debate is really more of their underlying philosophical foundations and assumptions
• Tycho Brahe


  • Danish Astronomer made some of the most accurate ever observations with the naked eye in the late 16th century. He disproved aristotle's concept of unchanging universe when he saw a new star in constellation of cassiopeia in 1572. This was later identified as a supernova. His model of the universe was both helio and geo centric with the planets revolving around the sun
• Johannes Kepler


  • Based on the Copernican model of the universe as well as the data collected by Brahe, Johannes Kepler produced an improved heliocentric model of universe, his model stated that the planets revolve around the sun in ellipses not circles and with the sun located at anyone of two foci in those ellipse
• Kepler's Laws of Planetary Motion


  1. Law of Ellipse: The orbit of each planet about the Sun is an ellipse with the Sun at one of the foci of the ellipse

  2. Law of Equal Areas: The line joining the Sun and the planet (called the "radius vector") sweeps over equal areas in equal times as the planet travels around the orbit

  3. Law of Period: The square of the period of revolution (time for one complete orbit) of a planet around the Sun is proportional to the cube of the average distance of the planet from the Sun

  
• Aristotle's view of motion


  It requires a force to make an object move in an unnatural manner - or, more simply, "motion requires force". He categorized motions as either "natural" motions or "violent" motions
• Galileo's laws of motion


  • Developed the concept of motion in terms of velocity (speed and direction) through the use of inclined planes
  • Developed the idea of force, as a cause for motion
  • Determined that the natural state of an object is rest or uniform motion, i.e. objects always have a velocity, sometimes that velocity has a magnitude of zero = rest
  • Objects resist change in motion, which is called inertia
• Galileo rolled balls along surfaces tilted at different angles. When ball rolls downward, it moves with Earth's gravity, and its speed increases. When ball rolls upward, it moves against gravity and loses speed. When ball rolls on level plane, it doesn't move with or against gravity
• Five Planets


  Mercury, Venus, Mars, Jupiter, Saturn