Geocentric Model - Earth is the center of the Universe
HeliocentricModel - Sun is the center of the universe
Thales - flat earther; Earth is a disc floating on water
Anaximander - Earth is a cylinder w/ a curved surface; Fire, Earth, Air, and Water are outside of Earth and supports the energy of Earth
Anaximander - created the sundial (ancient watch for time)
Pythagoras - first to originate a spherical Earth using observations; only observed, never went to space; geocentric
Pythagoras' observations:
North & South Constellation Planes
Sinking Ships
Lunar Eclipse
Pythagoras - first to say that Earth is round
North & South Constellation Planes - constellations are different for North and South poles
SinkingShips - if Earth was flat, ship will stay visible then gradually disappear; if not, ship will appear to sink until only top is visible.
LunarEclipse - Pythagoras observed that the Earth's shadow on the moon is round, not flat.
MusicofSpheres - Pythagoras' term for the solar system; motion of planets are mathematically related to sounds and numbers
Plato - elements (fire, water, air, earth, gaia/energy) are equally distributed around the planet
Plato - Earth is a globe with elements in every direction equidistant from the center
Plato - stars & universe is perfect, ethereal/divine, unchanging/eternal
EudoxusofCnidus - homocentric model: celestial spheres share Earth as their common center; creator of the 1st geocentric model
Eudoxus of Cnidus - According to him, there are 27 interconnected geocentric spheres.
Aristotle - geocentrism believer; said that a prime mover drives the motion of planets
Aristotle - believed that stars are fixed points, rotating on a single spherical sphere (56 spheres)
Aristotle - added 3 spheres to Jupiter & Mars, 4 spheres to Sun, Moon, Venus, and Mercury (to Eudoxus' model)
Eratosthenes - 1st to use math to measure the planet; gave the most accurate size during their time
ClaudiusPtolemy - Earth's a sphere; stars are fixed bodies; planets independently move and sometimes reverse; geocentrism believer
Ptolemy - His model contained a deferent, epicycle, and equant
Deferent - circular path in which planets move
Epicycle - circles where planets move
Equant - point close to the orbit's center (not the actual center)
Aristarchus of Samos - 1st to place Sun at the center of the universe; Earth revolves around Sun in a circular orbit; also believed that stars and sun are fixed
NicolausCopernicus - corrected geocentric theory and proposed heliocentric model with the following:
Earth's the only planet that moves around the Sun
Earth rotates daily on its axis and revolves around the Sun yearly
Earth has yearly tilting of its axis
Retrogrademotion of planets is explained by Earth's motion
Distance from Earth to sun is smaller than Earth to stars
RetrogradeMotion - point where planets are moving "closer" but actually just move faster on its orbit; rotational motion of an object in the direction opposite the rotation of its central/primary object (Earth)
TychoBrahe - 1st to design and build huge instruments to make precise measurements of planets' positions; geo-heliocentric proponent (planets revolve around the Sun, and the Sun revolves around the Earth)
TychoBrahe - discovered supernova in the constellation Cassiopeia (1572); witnessed and recorded 2 in total in his study of the heavens (contradicted Aristotle's idea that stars are unchanging)
TychoBrahe - Johannes Kepler's instructor/teacher
GalileoGalilei - 1st to use telescope and discovered the following:
sunspots on the Sun
Lunar craters
phases of Venus
4 moons of Jupiter
supernova
identical size of the Stars
SidereusNuncius - i.e. The Starry Messenger; Galilei's book
JohannesKepler - created the 3 laws of Planetary motion
FirstLaw (Planetary Motion) - orbits of planets are elliptical w/ the sun as the focus; has aphelion (point farthest from Sun) and perihelion (point nearest to Sun)
SecondLaw (Planetary Motion) - imaginary line drawn from the Sun to the planet sweeps out equal areas n equal time intervals (faster during perihelion, slower in aphelion)
Third Law - cube of radius of the orbit of a planet around the sun is proportional to the square of its period of revolution.