Post on 11-Jan-2016
transcript
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
You are here
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