MAN AND THE UNIVERSE

• Absolute truth

  Existence of an absolute truth
• Limitations in information

  • No complicated gadgets/access to limitless amount of information or data
• Religion

  People accept truths around them based on their belief
• Popularity


  With the digital world, information can be accessed although challenged with distinguishing what is true and what is not
• Different descriptions of a flat Earth can be found in the annals of ancient civilizations worldwide

  • Views vary because of limitations to information
• Earth was flat and circular

  • The earth was not only flat, but also circular. In a verse of Isaiah, "He who sits above the circle of the earth" (Isaiah 40:22)
• The earth was square and stationary
• Thales (628 - 548 B.C.)


  Described the earth as a disk floating on water

  was a cosmologist

  lived in the island of Miletus

  was mentioned by Aristotle as he was able to explain phenomena about natural things using observations, hypothesis making, and making conclusions

  more on empirical observations

  a precursor of science

  began the dawn of scientific method
• Anaximander (610 - 545 B.C.)


  Described the earth as a cylinder and its surface is curved

  believed in geocentrism

  contributed the sundial made up of a flat disk to tell time
• Pythagoras (570 - 490 BC)


  He was the first one to originate a spherical earth using observations: North Celestial Poles (NCP) & South Celestial Poles (SCP) Constellations, Sinking Ships, Partial Lunar Eclipse
• Pythagorean Model


  Earth is round

  Heavenly bodies move in circles

  Earth is at rest at the center, and everything rotates around it

  "The music of spheres" (motion of planets were mathematically related to musical sounds and numbers)
• Plato (428 - 348 BCE)


  He quoted that the earth is a form of a globe having its extremes in every direction equidistant from the center

  Ancient Astronomy: Believed that the universe is perfect or ethereal and unchanging, Described the stars in the outer space as ETERNAL and DIVINE,

  [Geocentric] "Saving the Appearances": What uniform and ordered circular motion must be assumed for each of the planets to account for their apparently irregular annual paths?

  • planet Mars went from east to west to west to east
• Eudoxus of Cnidus (390 - 337)


  Attempted to answer Plato using the Homocentric Model where celestial spheres share one common center – earth

  1st model of geocentric model

  Still wasn't able to answer Plato's question

  According to him, there are 27 interconnected geocentric spheres
• Aristotle (384 - 322 BCE)


  Believed that the Earth is fixed at the center of the solar system and that everything revolves around it

  Added to his model the four known elements of the universe (fire, air, water, earth)

  His model proved that the earth is spherical; believed that all stars are fixed points which rotate on a single celestial sphere; has 56 spheres

  
  

  Prime mover : drives the motion of the planets, In conjunction to Eudoxus' model

  
  

  In conjunction to Eudoxus' model, he added 3 spheres to Jupiter and Mars; 4 spheres to Sun, Moon, Venus, and Mercury
• Eratosthenes (276 - 194 BCE)


  Ancient scholars tried to provide proof of a spherical Earth and its circumference through calculations by using a stick (40,000 km)

  It was Eratosthenes who gave the most accurate size during their time
• Claudius Ptolemy (90 - 168 CE)


  Earth is a spherical object

  The stars are fixed bodies attached to a solid spherical exterior part of the universe

  Planets moved independently of the fixed stars and that sometimes, the planet seem to reverse their motion
• Ptolemy's Model


  Shows the deferent (circular path in which planets moves) and epicycle (circle where planets move)

  Proposed the equant (a point close to the orbit's center)

  Was able to answer Plato's question
• Aristarchus of Samos (310 - 230 BCE)


  Lived during the time of Aristotle

  He stated that the sun and stars are fixed
• Aristarchus' Model

  1st to place the sun at the center of the universe (HELIOCENTRIC)

  The sun and the stars are fixed

  The earth is revolving around the sun in a circular orbit
• Nicolaus Copernicus (1473 - 1543)


  Corrected the geocentric theory and proposed the Heliocentric Theory with the following postulates:

  • Earth is considered as only one of the planets that move around the sun
  • Earth rotates on its axis daily and revolves around the sun once a year
  • Earth experiences an annual titling of its axis (Explains the occurrence of different seasons)
  • The retrograde's motion of the planets is explained by earth's motion
  • The distance from earth to sun is small compared to earth's distance from the stars
• Retrograde Motion


  In astronomy is, in general, orbital or rotational motion of an object in the direction opposite the rotation of its primary, that is, the central object

  • Motion of heavenly bodies is from WEST TO EAST
• Copernicus' Model


  Celestial motions are uniform, infinite, and circular

  Planets revolved around the sun

  Earth's motion explains the retrograde motion of the other planets

  Earth spins on a tilted axis, which accounts for the seasons
• Tycho Brahe (1546-1601)

  Modified the geocentric model of the universe

  Designed and built huge instruments used to make precise measurements of the positions of the planets

  Discovered supernova in the constellation Cassiopeia in 1572

  Made observations of planetary motions that are important to the development of Kepler's Laws and other models of the solar system
• Geo-Heliocentric Model

  Tycho Brahe's model of the universe was both helio and geocentric, with the planets revolving around the sun, and the sun revolving around the earth.

  In his studies of the heavens, he witnessed and record two supernovae, which opposed Ptolemy's idea that the stars were unchanging.
• Galileo Galilei (1564 - 1642)

  Using his telescope:

  • He discovered sunspots and the rough surface of the moon
  • He discovered the 4 famous moons of Jupiter known as Galilean moons
  • He discovered that Venus has phases like the moon

  Was arrested as he contradicted the teachings of the Church and excommunicated him

  His contributions were only recognized after his death and the Church, specifically the Pope, apologized and removed his excommunication
• Johannes Kepler (1571 - 1639)

  Thanks to enormous and meticulous data collected by his mentor Tycho Brahe, Kepler Laws of Planetary Motion: The Fact of Today

  • 1st Law: Ellipses
  • 2nd Law: Equal Areas
  • 3rd Law: Harmonies
  • Astronomical Unit: average distance between Earth and the Sun, which is about 93 million miles or 150 million kilometers; usually used to measure the distances within our Solar System
• 2 major distinct characteristics that differentiate it from Ancient Astronomy are:

  1. The observations became more quantitative in nature, through computations, equations, formulas and numbers

  2. The theories formulated are based on logical and mathematical concepts
• North Celestial Poles (NCP) & South Celestial Poles (SCP) Constellations

  The North Star was believed to be at a fixed position in the sky. However, when the Greeks traveled to places nearer the equator, like Egypt, they noticed that the North Star is closer to the horizon.

  • If the earth is flat, the stars should be in a fixed position.
• Sinking Ships

  If the earth was flat, then a ship travelling away from the port from an observer should become smaller until it disappeared. However, the Greeks observed that the ship became smaller and then its hull disappeared first before the sail as if it was being enveloped by the water until it completely disappeared.
• Partial Lunar Eclipse

  A curved shadow was displayed from the partial lunar eclipse
• 1st Law: Ellipses

  • The orbits of the planet are ellipses, with the sun at one focus.
  • Perihelion: point nearest to the sun
  • Aphelion: point farthest to the sun
• 2nd Law: Equal Areas

  • Planets travel faster during perihelion, travel slower during aphelion
• 3rd Law: Harmonies

  • the larger the planet's orbit, the longer the revolution
  • the square of the revolutions of the planet are directly proportional to the cubes of their average distances
• Astronomical Unit

  Average distance between Earth and the Sun, which is about 93 million miles or 150 million kilometers; usually used to measure the distances within our Solar System.