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