1. The Cosmic Engine

3. Millions of stars (suns)
Mercury
Planets
Venus
Earth
Gravity
Mars
Powered by nuclear reactions
Sun is a star
Jupiter
Solar System
Saturn
Uranus
Neptune
Millions of stars (suns)
Milky Way
Galaxy
Stars orbit galactic centre
Gravity
Billions of galaxies
Universe
Universe is expanding

4. Scale of the Universe

5. A Little History
Up until 200 years ago, it was all about the solar system.
1500 year battle over geo-centric vs helio-centric
Geo-centric: Geo = earth Centric = centred around
Everything revolved around the Earth
Helio-centric: Helio = sun Centric = centred around
Everything revolves around the sun

6. It all started with Aristotle & Aristarchus
~330BC
Aristotle: Philosopher – Sun, moon, planets & stars orbit Earth on crystal spheres
Geo – centric
~240BC
Aristarchus: Philosopher – Earth & planets orbit the sun on crystal spheres, stars are on a fixed sphere very far away.
Helio– centric

7. Claudius Ptolemy - ~120AD Geo-centric
It explained retrograde motion of planets
Based on evidence, not philosophy
It worked!
It became part of religious doctrine

8. Ptolemy

9. Nicolaus Copernicus
Helio-centric model – Earth & planets orbit the sun on crystal spheres
It was simpler, and possibly more “correct”, but it didn’t work any better, therefore it was largely rejected.
Also rejected for religious reasons

10. Copernicus

11. Tycho Brahe 1546-1601 Believed in a geo-centric universe
He made amazingly accurate measurements (without the aid of a telescope)
Kepler was his student (begrudgingly!) and he used Tycho’s results for the next great step in astronomy

12. Tycho Brahe

13. Johannes Kepler
Used Tycho’s data and worked with Copernicus’ model
Made the leap from circular to elliptical orbits
His model worked, but there was no mechanism to hold the solar system together
It was therefore largely rejected

14. Kepler

15. Galileo Galilei 1564-1642 Used the first telescope in 1609
3 significant observations:
Moons of Jupiter
Phases of Venus
Craters on the moon
Heavens not “perfect”
Labelled a heretic and forced to recant. He was only forgiven in 1992 (and then “pardoned”!)

16. Galileo

17. Sir Isaac Newton
Newton changed EVERYTHING in physics (and in maths!)
In this story, he proposed the first theory of gravity – this was the missing piece of the Kepler model
He was also able to predict the model that Kepler had proposed – this is science at its best

18. Newton

19. But this is only the beginning…
It took another 200 years to start to understand the universe outside of the solar system.
They hadn’t even begun to explain nebulae, galaxies, black holes, quasars, pulsars and all the other cool things in the universe.