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The Cosmic Engine. 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. Stars orbit galactic centre. Galaxy. Gravity. Billions of galaxies. Universe. - PowerPoint PPT Presentation
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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
Nicolaus 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
Copernicus
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
Tycho Brahe
Johannes Kepler 1571 - 1630
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
Kepler
Galileo Galilei 1564-1642Used 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”!)
Galileo
Sir Isaac Newton 1642-1727
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
Newton
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.