Really, just how important and Really, just how important and significant are you…………?significant are you…………?

CosmologyCosmologyThe study of the The study of the

contents, structure, and contents, structure, and evolution of the universe evolution of the universe

from the beginning of from the beginning of time……to the future. time……to the future.

Was Monty Python right?Was Monty Python right?

““that’s orbiting at 19 miles a second”that’s orbiting at 19 miles a second”Calculate if this is in any way an accurate Calculate if this is in any way an accurate figure?figure?

What data do you need to do this?What data do you need to do this?

Earth – Sun distance = 9.29x10Earth – Sun distance = 9.29x1077 Miles Miles

Year = 365.25 daysYear = 365.25 days

CalculationCalculation

Orbit Radius = 9.29x10Orbit Radius = 9.29x1077 miles milesCircumference= distance travelled= 2Circumference= distance travelled= 2ππRR

= 2 x = 2 x ππ x x 9.29x109.29x1077

= = 583707915 miles583707915 milesSpeed = Distance ÷ Time Speed = Distance ÷ Time (Time =365.25 days)(Time =365.25 days)

Speed = 1598105 miles/daySpeed = 1598105 miles/day

or 18.5 miles per second…Pretty close!!!or 18.5 miles per second…Pretty close!!!

Our Solar SystemOur Solar System

Lets start closer to home….Lets start closer to home….

watch the video “Our Solar Sytem” and watch the video “Our Solar Sytem” and make notes.make notes.

Cosmology Projects/PresentationsCosmology Projects/Presentations

The Earth, Moon and SunThe Earth, Moon and SunThe MoonThe MoonThe Solar SystemThe Solar SystemStars & ConstellationsStars & Constellations

Each group will also have to explain one Each group will also have to explain one topic from Cosmology Mathematics.topic from Cosmology Mathematics.

The Earth, Moon & SunThe Earth, Moon & Sun

Night & DayNight & DaySeasonsSeasonsSolar EclipsesSolar EclipsesSolar FlaresSolar FlaresAurora BorelalisAurora Borelalis

The MoonThe Moon

The Phases of the moonThe Phases of the moonThe Dark Side MoonThe Dark Side MoonLunar EclipseLunar EclipseTidesTides

Solar System ModelSolar System Model

Demonstration of the size and scale of our Demonstration of the size and scale of our solar systemsolar system

ConstellationsConstellations

Identify the Great Bear, The Big Dipper, Identify the Great Bear, The Big Dipper, The PloughThe Plough

Identify the North Star (Polaris)Identify the North Star (Polaris)Orion and The Horse Head NebulaOrion and The Horse Head NebulaTaurusTaurusPlaeidesPlaeidesCasseopiaCasseopiaStar MapsStar Maps

Cosmology MathematicsCosmology Mathematics

Astronomical units (AU)Astronomical units (AU)Parsecs (pc)Parsecs (pc)Light years (ly)Light years (ly)Ellipses Ellipses

CosmologyCosmology11 Our Solar SystemOur Solar System

How it all started……

‘Geocentric’

Ptolemei & Aristotle

Earth is the centre of the

universe

Copernicus (1609/1637) Present

idea of planetsrotating around the sun

versus

‘Heliocentric’ Solar System

CosmologyCosmology

Kepler’s Laws (1609)Describe the motion of the planets around the sun.

Kepler IThe orbit of a planet around the sun is an ellipse with the sun at one focus.

Kepler IIKepler II

2 A line joining a planet and the sun sweeps out equal areas in equal times.

Click Picture for K2a Movie

clack for K2b Movie

Kepler IIIKepler III

Describes a relationship between the radius of the planets (average distance to the sun) and the time taken for one complete orbit.

T2 is proportional to R3

Click for K3 Movie

CosmologyCosmology11 Our Solar SystemOur Solar System

Kepler’s Laws (1609)Answer the following questions based on Kepler’s laws:

1 a) Compare planetary ellipses to circles. In what way are they different?

b) Use your worksheet ‘Structure and size of the universe’ to find out

which planet is furthest off the circle and which one is closest to a circle.

What about ‘Mars’- Kepler’s favourite…?

c) Draw an ellipse with its two focal points and the two radii.

CosmologyCosmology11 Our Solar SystemOur Solar System

Kepler’s Laws (1609)Answer the following questions based on Kepler’s laws:

2 a) Use Kepler’s second law of equal areas describe the planets speed

when its orbit is furthest from the sun and when its closest to the sun.

b) Does the force that keeps the planet on its path change? Explain.

3 How does the period of rotation of a planet change if the average

distance to the sun a) doubles or b) triples.

The Big Bang TheoryThe Big Bang Theory- Our Expanding Universe - Our Expanding Universe

Cosmology is the search for origins.  Cosmology is the search for origins.  It seems as if everyone wants to It seems as if everyone wants to know how the Universe began.  know how the Universe began. 

The Big Bang theory is the result of The Big Bang theory is the result of several important observations.  several important observations. 

In 1927, Edwin Hubble first observed In 1927, Edwin Hubble first observed that light from distant galaxies is red that light from distant galaxies is red shifted and that galaxies are moving shifted and that galaxies are moving farther and farther away from us.  farther and farther away from us. 

Second, he determined that the Second, he determined that the farther away a galaxy is from us, the farther away a galaxy is from us, the faster it is receding from us. faster it is receding from us.

Hubble’s LawHubble’s Law What does this What does this

graph tell us?graph tell us? Note how there is a Note how there is a

clear proportionality clear proportionality between distance between distance and recessional and recessional velocity. velocity. 

This proportionality This proportionality is known as the is known as the Hubble Law.  Hubble Law. 

The slope of this The slope of this line, with line, with dimensions of dimensions of velocity over velocity over distance, is called distance, is called the Hubble the Hubble Constant (H). Constant (H). 

Recessional VelocityRecessional Velocity

The graph shows that the The graph shows that the recessional velocity (the recessional velocity (the speed a galaxy is moving speed a galaxy is moving away from us) is away from us) is proportional to the proportional to the distance from us.distance from us.

i.e. stars further away i.e. stars further away from us are moving away from us are moving away from us faster than stars from us faster than stars closer to us!closer to us!

What is the inference from Hubble’s What is the inference from Hubble’s LawLaw

Almost all Galaxies are red shifted and are Almost all Galaxies are red shifted and are thus moving away from us (The Milky thus moving away from us (The Milky Way)Way)

The most The most Distant galaxies Distant galaxies exhibit the most exhibit the most red-shift, thus the red-shift, thus the most distant most distant galaxies are galaxies are moving away from moving away from us fastest.us fastest.

The Hubble ConstantThe Hubble Constant Let us look more closely at the Let us look more closely at the

slope of the Hubble Law Graph.slope of the Hubble Law Graph. Slope = Velocity/Distance (Hubble Slope = Velocity/Distance (Hubble

Constant)Constant) The inverse of the Hubble The inverse of the Hubble

Constant then has the dimension Constant then has the dimension of time, and can be taken as an of time, and can be taken as an estimate of the age of the estimate of the age of the Universe!  Universe! 

The Hubble Constant has been The Hubble Constant has been found to be between 50 and 100 found to be between 50 and 100 km/s per kiloparsec. km/s per kiloparsec.

The Universe has thus been The Universe has thus been expanding for expanding for 8 to 15 billion 8 to 15 billion yearsyears

The Future of the Universe?The Future of the Universe? The gravitational attraction will The gravitational attraction will

eventually overcome the eventually overcome the expansion. The Universe will stop expansion. The Universe will stop expanding and then collapse to an expanding and then collapse to an eventual big crunch This is called a eventual big crunch This is called a closed universeclosed universe..

Alternatively the expansion slows Alternatively the expansion slows to zero ‘at infinity’. This is called a to zero ‘at infinity’. This is called a flat universe.flat universe.

If there is not enough mass for its If there is not enough mass for its gravitation effect to overcome the gravitation effect to overcome the expansion, the Universe will expansion, the Universe will continue to expand forever. This is continue to expand forever. This is called an called an open universeopen universe..

A closed universe might rebound A closed universe might rebound forever – a big bang eventually forever – a big bang eventually resulting in a big crunch which resulting in a big crunch which rebounds into a big bang and so rebounds into a big bang and so on. The whole Universe may be a on. The whole Universe may be a gigantic oscillator!gigantic oscillator!

Don’t Worry - if there is to be a Big Crunch it won’t be for a very, very

long time!