WEEK 1

• Greeks divided the universe into domains: celestial domain and the terrestrial domain.
• First observation leading to the belief that the Earth is round is lunar eclipses.
• Second observation leading to the belief that the Earth is round is by measuring the length of the shadow cast by identical poles perpendicular to a flat surface that is tangential to the earth's radis at varius distant locations
• Pythagoras said that the Universe is mathematical; mathematics as the best way to express truth aboout the Universe; Sun, moon, and Earth are spherical; placed Earth as the center of the Universe.
• Plato stated that attainment of perfection as absence of change; mathematical sy,,etries to demonstrate perfect shapes; celestial spheres being crystalline and contains the moon, the Sun and the stars; explaining the shadows as his description or framework on how to look at the Universe in particular that the daiky and annual patterns of the sky must have a greater reality besides it appearance.
• Eudoxus followed previous models of the universe but added auxiliar spheres to provide appropriate tilt to the planets' path.
• Aristotle said that the terrestrial domain contains 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.
• As the earth orbits the sun, the sun appears to move eastward with respect to the stars. The sun circles the celestial sphere once every year.
• fire signifies alteration.
• air signifies natural motion
• water signifies violent motion
• earth signifies stable
• ether is the perfect motion: circular and constant speed
• The Celestial domain is perfect, therefore it can only be made up of the perfect substance called ether which can only move in perfect motion: circular in path and constant in speed.
• The Terrestrial domain objects are considered imperfect and that the tendency of things to attain perfection is the cause of their motion.
• The Terrestrial domain also said that the composition of elements tend to move towards the center or away from it.
• Ptolemaic model: The model of the universe proposed by the Greek astronomer and mathematician Ptolemy.
• If the earth rotates about its axis, given the calculated circumference of the earth as measured by eratosthenes all objects must be moving at about 2,000 kph.
• the spinning earth would cause object to fly out, which does not happen
• falling things would veer towards the west as they fall, the arrows are not seen to veer away fro the intedned target
• spinning or orbiting earth would require constant amount of force to keep moving
• no parallax of the stars since the annual pattern of the planets does not change
• the parallax happens in differing degrees depending on the distance of the object from the observer
• Tycho Brahe was a danish nobleman, astronomer, and writer known for his accurate and comprehensive astronomical observations such as the supernova explosion of nov. 11, 1572 named Nova Stella, comet in 1577, better and more reliable data sets.
• Tychonian Quadrant is an instrument used to study and observed the heavens.
• Heliocentric is the sun centered model
• geocentric is the earth centered model
• The new object does not show daily parallax against the background stars this must mean that it is farther than the moon and planets
• Brahe did discover nova stella, accurate astronomical data for his time, proved that comets are found in the celestial domain, removed the necessity of crystalline celestial spheres
• Johannes Kepler is a german astronomer, mathematician, and astrologer. best known for his laws of planetary motion.
• Three laws of planetary motion are orbit/ellipse, equal area, period
• law ellipse states that the orbit of each planet about the sun is an ellipse with the sun at one of the foci of the ellipes
• Law of equal areas states that the line joining the sun and the planet callred the radius vector sweeps over all equal areas in equal times as the planet travels around the orbit.
• Law of period states that the period of revolution of a planet is proportional to the cube of the average distance of the planet from the sun
• Anima motrix which means motor life or prime mover is initially thought by aristotle on which it is the idea that it is the force that pulls our planet towards the sun in orbit, in other words it is gravity, but an ancient understanding of it.