Astronomers
Published on Dec 03, 2015
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PRESENTATION OUTLINE
ARISTOTLE
- 384-322 BCE
- thought Earth was center of all things
- model placed moon, sun, planets, and stars in series of circles around Earth
- if earth went around sun, relative positions of stars would change
- Geocentric (earth centered)
GEOCENTRIC MODEL
- description of cosmos
- earth is at orbital center of all celestial bodies
Aristarchus
- 312-230BCE
- proposed heliocentric model of solar system
- model not widely accepted at time
- 1st to try to measure relative distances to moon & sun
HELIOCENTRIC MODEL
- places sun as center of universe w/ planets orbiting around it
- replaced geocentrism
PTOLEMY
- 100-170 BCE
- "wheels-on-wheels" system-allowed prediction of motion of planets
- geocentric model-used by scientists for next 14 centuries
- celestial body moves at constant speed in perfect circle
- planets moved in circles that in turn moves on bigger circles
COPERNICUS
- 1473-1543
- made model of solar system with sun at center
- heliocentric
- he used circular orbits
KEPLER
- 1571-1630
- found ellipses are best path
- planetary orbits are ellipses with sun at 1 focus
- planets move faster in orbit closer to sun
- distance of planet from sun vs time for 1 orbit
GALILEO
- 1564-1642
- used scientific method
- observed moons Io, Europa, Callisto, Ganymede orbiting Jupiter
- showed that earth wasn't the only object that could be orbited
- supported heliocentric model
NEWTON
- 1642-1727
- laws of motion
- universal gravitation
- built first reflecting telescope
EDWIN HUBBLE
- 1889-1953
- Hubbkle's law~universe is expanding
- believed the frequency of light could decrease as moves through space
- metric expansion of space
