140 likes | 153 Views
Model of the Solar System. Who is This Greek Guy?. Two models of the Solar System. Aristotle Lived more than 2000 years ago in Greece -Geocentric Model: -Earth is the centre of the solar system and all other bodies rotate around it -Earth was stable and motionless
E N D
Two models of the Solar System • Aristotle • Lived more than 2000 years ago in Greece -Geocentric Model: -Earth is the centre of the solar system and all other bodies rotate around it -Earth was stable and motionless -Accepted for over 2000 years -Planets is greek for ‘wanderers’
Geocentric Model Problem: -Retrograde motion: the apparent backwards motion of planets as a faster orbiting planet passes it. - Ex. Earth travels around the Sun faster than Mars How did we overcome this??
A solution was found by Ptolemy: -Who lived around 140 AD -he proposed the idea of epicycles (small circles) on the planetary orbits and these explained retrograde motion
But there was a problem with Ptolemy’s epicycles: -very complicated; still not accurate in predicting planet positions
Nicolaus Copernicus (Late 1400’s): - Heliocentric Model: Sun centered model of the solar system
Kepler • A mathematician • Made model more accurate by finding that orbits were ellipses rather than circles Problems: - no knowledge of gravity; still not accurate in predicting planet positions.
Clinching Evidence: • Galileo (1609) • Developed a telescope • Saw moons orbiting Jupiter • Newton (1667) - developed laws of motion and gravity based on Kepler’s work and which are true for earthly and celestial bodies