Do now!Do now!Can you continue the gravity questions you

started yesterday?

Development of models of the Solar Development of models of the Solar system/universesystem/universe

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Astronomical observationsAstronomical observations

The pattern of the The pattern of the stars remains the stars remains the same from night to same from night to night (over the time of night (over the time of a life-time)a life-time)

These patterns have These patterns have been labelled been labelled constellationsconstellations

Orion’s belt

Astronomical observationsAstronomical observations

The constellations do The constellations do not appear in the same not appear in the same placeplace

Over the period of one Over the period of one night they appear to night they appear to rotate around the pole rotate around the pole starstar

Some stars rise above Some stars rise above the horizon during the the horizon during the night, and some set night, and some set behind it.behind it.

Astronomical ObservationsAstronomical Observations

This same movement is continued during the day. This same movement is continued during the day. The sun rises in the east and sets in the west. The sun rises in the east and sets in the west. Maximum height at midday (in the south in the Maximum height at midday (in the south in the Northern hemisphere.Northern hemisphere.

Constellation positionConstellation position

The constellations The constellations have the same relative have the same relative positions from night to positions from night to night.night.

‘‘

View toward horizon from 59°54'N 11°E, azimuth 0° (N)View toward horizon from 59°54'N 11°E, azimuth 0° (N)

Place to placePlace to place

The constellation you can see also depends on The constellation you can see also depends on where you arewhere you are

I can’t see the pole star!

I’m on top of the world!

Constellation positionConstellation position

The location of the pole star varies from The location of the pole star varies from night to night as we go through the year, so night to night as we go through the year, so different constellations may be visible at different constellations may be visible at different times of the year.different times of the year.

View toward horizon from 59°54'N 11°E, azimuth 0° (N)View toward horizon from 59°54'N 11°E, azimuth 0° (N)

PlanetsPlanets

Some objects that we Some objects that we can see a night can see a night behave differently!behave differently!

Their position DOES Their position DOES change relative to the change relative to the background of stars.background of stars.

These objects are These objects are called planets (derived called planets (derived from the Greek word from the Greek word for “wanderer”).for “wanderer”).

PlanetsPlanets

The planets can sometimes exhibit The planets can sometimes exhibit retrograderetrograde motion over the course of several motion over the course of several nights.nights.

The moonThe moon

The moon’s observed motion across the night The moon’s observed motion across the night sky is different again. sky is different again.

It takes part in the nightly rotation around the It takes part in the nightly rotation around the pole star, but it also wanders.pole star, but it also wanders.

PhasesPhases

The moon’s appearance changes over the The moon’s appearance changes over the course of a month. We say it has course of a month. We say it has phasesphases..

The Moon's PhasesThe Moon's Phases

Models of the UniverseModels of the Universe

Aristotle (384-322 BC)Aristotle (384-322 BC)Wisdom is the reward you get for a lifetime of

listening when you'd rather have been

talking.

Aristotle’s UniverseAristotle’s Universe

Earth at centre (Earth at centre (geocentricgeocentric)) Other objects attached to concentric perfect Other objects attached to concentric perfect

crystal spheres turning at slightly different crystal spheres turning at slightly different speedsspeeds

All “fixed” stars were attached to the final All “fixed” stars were attached to the final spheresphere

Aristotle’s UniverseAristotle’s Universe

Ptolemy’s (AD 85 – 165) adaption of Ptolemy’s (AD 85 – 165) adaption of Aristotle’s ideasAristotle’s ideas

To explain the retrograde motion of some To explain the retrograde motion of some planets, he allowed each planet to move in a planets, he allowed each planet to move in a small circle (an small circle (an epicycleepicycle))

The centre of the epicycle moved on a The centre of the epicycle moved on a bigger circle called a bigger circle called a deferentdeferent..

Earth is still at the centre (Earth is still at the centre (geocentricgeocentric))

Ptolemy’s adaption of Aristotle’s Ptolemy’s adaption of Aristotle’s ideasideas

The Universe of Aristotle and PtolemyThe Universe of Aristotle and Ptolemy

Heliocentric modelsHeliocentric models

Sun-centred (Sun-centred (heliocentricheliocentric)) First proposed by First proposed by AristarchusAristarchus (2 (2ndnd century century

BC), but it has come to be associated with BC), but it has come to be associated with CopernicusCopernicus (1473-1543) (1473-1543)

Orbits are still taken to be circularOrbits are still taken to be circular Explains retrograde motion of planetsExplains retrograde motion of planets

Heliocentric modelsHeliocentric modelsThe Copernican Model: A Sun-The Copernican Model: A Sun-CenteredCentered Solar System Solar System

This model also explains why Mercury and Venus always appear close to the sun in the sky To account for

slight differences between the model and actual observations, Copernicus was forced to add epicycles too!

GalileoGalileo

"All truths are easy to understand once they are discovered; the point is to

discover them."

GalileoGalileo

His observations with one of the first His observations with one of the first telescopes added further support to the telescopes added further support to the Copernican viewCopernican view

Galileo’s observationsGalileo’s observations

There are mountains on the moonThere are mountains on the moon Venus has phases (like the moon) and Venus has phases (like the moon) and

appears to change sizeappears to change size Jupiter has objects orbiting it (moons)Jupiter has objects orbiting it (moons) There are dark spots on the sunThere are dark spots on the sun The sun rotates and the spots on the The sun rotates and the spots on the

surface movesurface move

Galileo in troubleGalileo in trouble

In 1633 he was tried by the catholic Church In 1633 he was tried by the catholic Church and forced to recant his ideas. He remained and forced to recant his ideas. He remained under house arrest for the rest of his lifeunder house arrest for the rest of his life

KeplerKepler

At the same time as Galileo, At the same time as Galileo, Johannes Johannes KeplerKepler (1571-1642) was adapting (1571-1642) was adapting Copernicus’s modelCopernicus’s model

His new model gave very good agreement His new model gave very good agreement with observationswith observations

Kepler’s modelKepler’s model

Each planet orbits the Each planet orbits the sun in an ellipse, with sun in an ellipse, with the sun at one focusthe sun at one focus

Universal GravitationUniversal Gravitation

If I have ever made any valuable discoveries, it has been owing more to patient attention, than to

any other talent.

Isaac Newton (1642 – 1727)

Universal GravitationUniversal Gravitation

Newton came up with a physical explanation Newton came up with a physical explanation for Kepler’s modelfor Kepler’s model

Newton proposed that every object in the Newton proposed that every object in the universe attracts every other object with a universe attracts every other object with a force that is proportional to the masses of force that is proportional to the masses of the objects and inversely proportional to the the objects and inversely proportional to the distance between the objects squareddistance between the objects squared

UniversalUniversal Gravitation Gravitation

This law applies This law applies everywhereeverywhere in the in the universeuniverse

It can explain why an apple falls to It can explain why an apple falls to earth, but also why the moon stays in earth, but also why the moon stays in orbit around the earthorbit around the earth

GalaxiesGalaxies

Large collections of stars (100,000,000,000)Large collections of stars (100,000,000,000)

Edwin HubbleEdwin Hubble

In 1925 Edwin hubble found that distant In 1925 Edwin hubble found that distant galaxies are moving away from us. The galaxies are moving away from us. The further they are away, the faster away they further they are away, the faster away they are moving!are moving!

Big bangBig bang

Hubble’s discovery implied that in the past Hubble’s discovery implied that in the past the universe must have started from a single the universe must have started from a single point, the big bang! (about 13 billion years point, the big bang! (about 13 billion years ago)ago)

Stephen HawkingStephen Hawking

Mr Porter’s friend Stephen Hawking has Mr Porter’s friend Stephen Hawking has been working on the implications of this “Big been working on the implications of this “Big Bang singularity (black hole)Bang singularity (black hole)

That’s it!That’s it!

Mind map – pages 138 - 139Mind map – pages 138 - 139

Mind mapMind map

ColoursColours Pictures/drawingsPictures/drawings Few words (not complete sentences)Few words (not complete sentences)

Mr Porter

likes

dislikes

familyplaces

tea

newspapers

footballKirsten Dunst

teaching

red wine

dogsbanks Mr Bean

rudenessdogs

shopping

music

3 kids

wifeEngland

NorwayPNG

Peru

Tetley

Milk, no sugar

Guardian

Times

Independent Nottingham Forest

Spiderman

trumpet

physics

Gato negro

rockclassical

Alice

George

Louis

Alison

clothes

Poo!queuingBlackadder

NatwestPoo!

Oslo

Port Moresby

Lima

Twice European Champions Wimbledon

CD

Bristol University

cheap

Rush

Bruckner

12

10

9

21

Marks and Spencer

Norway!Lik lik hus

Brain map – pages 138 - 139Brain map – pages 138 - 139