The Cosmic Engine
Solar System
Universe
Venus
Mercury
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Planets
Gravity
Sun is a starPowered
by nuclear reactions
Millions of stars (suns)
Billions of galaxies
Milky Way
Stars orbit galactic centre
GravityGalaxy
Universe is expanding
Scale of the Universe
http://primaxstudio.com/stuff/scale_of_universe/
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 aroundEverything revolved around the Earth
Helio-centric: Helio = sun Centric = centred around
Everything revolves around the sun
It all started with Aristotle & Aristarchus
~330BCAristotle: Philosopher – Sun, moon, planets & stars orbit Earth on crystal spheres Geo – centric
~240BCAristarchus: Philosopher – Earth & planets orbit the sun on crystal spheres, stars
are on a fixed sphere very far away.
Helio– centric
Claudius Ptolemy - ~120AD
Geo-centric
It explained retrograde motion of planets
Based on evidence, not philosophy
It worked!
It became part of religious doctrine
Ptolemy
Nicholas Copernicus 1473 - 1543
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
