1. Solar System Theory Dr Ward

2. In The Beginning There Was... ● Celestial Sphere Model (Plato 427 to 347 BC) – Earth at centre – All objects around it placed on a sphere – Nothing outside this ● Aristotle (350 BC) – Crystalline rings holding celestial objects – Seven wandering 'planets' – Sun, moon, Mercury, Venus, Mars, Jupiter, Saturn

4. One Small Step For Mankind...

5. The Ptolemaic Universe ● Ptolemaic Universe (Ptolomy 150 AD) – Orbits are circular – Attempted to justify strange movement of planets due to Earth centred theory by introducing rings on rings To explain the continuing inconsistencies the model stated that the planets orbited on sphere that in turn orbited on concentric crystalline spheres ● This logic 'proved' that they were right!

6. If You're Wrong Just Use Spin ● Ptolomy had three beliefs – All motion in heaven is uniformly circular – Objects in heaven are made of perfect material – Earth is at the centre of the Universe ● Catholic church said this proved God controlled the heavens – Not a good idea to disagree – Ask Bruno (1548 to 1600) who was burnt at the stake during The Spanish Inquisition

7. NOBODY expects the Spanish Inquisition! Our chief weapon is surprise...surprise and fear...fear and surprise.... Our two weapons are fear and surprise...and ruthless efficiency.... Our *three* weapons are fear, surprise, and ruthless efficiency...and an almost fanatical devotion to the Pope.... Our *four*...no... *Amongst* our weapons.... Amongst our weaponry...are such elements as fear, surprise.... I'll come in again.

8. The New Deal: Heliocentric Models ● The Copernican Model (Copernicus 1473 – 1543) – Used naked eye to determine Sun at centre and stars did not orbit Sun – However, still assumed orbits were circular ● Gallileo (1564 to 1642) – Used the devils tool (a telescope) – Found that Sun rotated and Jupiter had four moons – Proved Copernican hypothesis ● Brahe (1546 to 1601) – Determined that comets further away than Moon – Retrograde step was to re-assume Earth at centre

9. The Heliocentric Model ● Keplar (1571 to 1630) – Brahes' assistant took things forward – Devised three laws; ● Orbits are elipses with Sun at one focus ● Planets sweep out equal areas in equal times ● Ratio of squares of revolutionary periods for two planets equal to ration of the cubes of their semi- major axes ● Newton (1642 to 1727) and Einstein ((1879 to 1955) – Took things to the current theory of the Universe – Next lesson