© Boardworks Ltd 2003 KS4 Earth and Beyond. © Boardworks Ltd 2003 What we once thought…… I...

© Boardworks Ltd 2003

KS4 Earth and Beyond


What we once thought……

I don’t think so!!!

Copernicus


The Solar System

What makes up the Solar System?

1. ___________

2. ___________

3. ___________

4. ___________

5. ___________

The Sun

The planets

Moons

Asteroids

Comets

Which of the above are light sources?

Our Sun is a star


The Sun

The Sun is the source of energy for life on Earth. Where does this energy come from?

What would happen on Earth if the Sun suddenly disappeared?

The Sun is powered by nuclear fusion reactions. Atomic nuclei are joined together (fused) due to the high pressures inside the Sun.

All plants would die (no photosynthesis), animals would die (no food source), temperatures would drop, there would be no light, it would lead to the end of all life on Earth.


The Sun and energy

Scientists were once confused.

If the Sun, they thought, was powered by chemical reactions how has it managed to stay ‘burning’ for millions of years?

There must have been another process producing the energy from the Sun…………. Nuclear Fusion.

What two elements constitute most of the Sun?

How old is the Sun?

Hydrogen and helium

Four and a half billion years


Nuclear fusion

In nuclear fusion reactions, lighter nuclei are joined together (fused)

……

….to form heavier atomic nuclei.

This releases massive amounts or energy.

In our Sun, a typical star, hydrogen is being fused into

helium, this provides the energy

for life on Earth.

When all the hydrogen is used

up, other elements will be fused

together to make even heavier

elements.

Not all elements are made in this way,

the heaviest elements, some of which are found in your body can only

be made when stars explode.


Stellar Evolution 1

Lighter stars like our Sun…..

Nebula collapses due to gravity

Forms a star like our

Sun

Expands to form a Red

Giant

Outer layers of star drift away to leave a dense White Dwarf

Very small nebula form failed stars


Stars a lot heavier than our Sun…..

Larger nebula collapses due to gravity

Forms a star more massive than our Sun

Expand to form Super-massive

Red Giant

Red Giant collapses violently in supernova

explosionSuper-dense Neutron Star

formed

Stellar Evolution 2


If the original nebula was massive enough, then when it goes supernova it leaves a star so dense that not even light can escape its gravitational pull.

This is called A Black Hole!

Some scientists believe that there are Black Holes at the centre of galaxies.

Homework Task:

If light can escape a Black Hole, then how do we see it?

Stellar Evolution 3


The life cycle of a star


Black Holes

How can you see a Black Hole?

You don’t (AND IT WOULDN’T BE BLACK).

You see the effect it has on nearby matter.

If there is a star nearby, matter from the star will spiral into the Black Hole and as it does so the matter emits X ray radiation which we can detect.

X rays


Put the following in a flow diagram to show the life cycles of stars. It has been started for you:

Nebula

White dwarf

Neutron star

The Sun

Red Giant

Supernova

Super-massive Red Giant

Star larger than our Sun

smaller nebula

larger nebula


The Lifecycle of a star:

Nebula

smaller nebula

larger nebula

White dwarf

The Sun

Red GiantNeutron star

Super-massive Red Giant

Star larger than our Sun

Supernova


Star questions:

1. What two elements make up most of our Sun?

2. What is a nebula?

3. What process has allowed the Sun to emit light and heat radiation over billions of years?

4. Which is the most dense, a white dwarf or a neutron star?

5. Describe the possible fate of a star similar to our Sun.

Hydrogen and helium

Cloud of gas and dust

Nuclear fusion

Neutron star

Red Giant White Dwarf


The Sun’s gravity:

1. What force keeps the planets in orbit around the Sun?

2. Which planet shown will feel this force ………..

a) The strongest? b) The weakest?

Not to scale!

Gravity


Where did the Sun come from?

This causes the “nebula” to collapse

Gravity causes a dust and gas cloud to condense into a smaller volume

As the nebula collapses, temperatures and pressures inside the nebula increase.

When the temperature and pressure are great enough

nuclear fusion starts.

Eventually gravity and the outward pressure of escaping energy is

balanced, and at this stage it is called a star.

Put the sentences in the correct order.


Satellites

1. What are the two types of satellite?

2. Give an example of each type?

3. Why are some satellites, like the Hubble Space Telescope shown, put into space?

Natural and artificial

Natural – The Moon

Artificial – Navigation, spy, military, weather, communications

So the Earth’s atmosphere does not get in the way.


Polar and Geo stationery

Geo stationery

Satellites spin around at the same speed as the Earth, stay above the same location on the Earth’s surface.

Polar

Satellites orbit around the poles, whilst the Earth spins underneath, allowing large areas of Earth to be seen.


Say if the satellites below have a polar orbit or a geo-stationery orbit:

Polar Geo stationery

Communications

Communications

Spy

Spy

Weather

Weather

Navigation

Navigation


Comparing orbits

Polar Geo stationery

Height of orbit

Orbital speed

Orbits per day

Orbit position

Example

Use a textbook or other resource to fill in the table below:

lower higher

faster slower

3-4 1

around poles above equator

weather communications


Can you put these in the correct size order, smallest first?

1. __________

2. __________

3. __________

4. __________

5. __________

Earth

The Sun

The Solar System

The Milky Way

The Universe

Earth

The Sun

The Solar System

The Milky Way

The Universe


Match the words and definitions:

A star

A planet

A galaxy

The Universe

The Solar System

There are nine of these in our Solar System. The Earth is one.

Our Sun is one.

Billions of stars together - ours is called the Milky Way.

The Sun, planets, moons, asteroids and comets make up this.

All the galaxies and everything else.


Identify the different bodies:

A galaxy A star The Universe


Red shifts

Listen to the noise a plane makes as it passes you……

As the plane approaches it sounds higher pitched……….

…then when it is moving away from you, it sounds

lower pitched.

This is due to the Doppler effect, the same thing happens with light. Approaching objects have the wavelength of the light they emit shortened (red-shifted), receding objects have the wavelength of light they emit increased (blue-shifted).


Hubble

Hubble was a famous scientist who examined the light from nearby galaxies. He noticed two things:

1. That most of the galaxies’ light was shifted towards the red end of the spectrum;

2. The further away a galaxy was, the more its light was red-shifted.

From these observations he concluded:

1. That most galaxies were moving away from our own;

2. The further away a galaxy was, the faster it was moving away from us;

3. And therefore he concluded that the universe is expanding.


Fate of the Universe Research

What is the possible origin and fate of the Universe?

Using a textbook, CD-Rom or the internet try to find two different theories about the origins and fate of the Universe.

Hints:

Cosmic microwave background radiation

The Big Bang

The Big Crunch

Hubble

Expanding Universe

Red-shifts

Open UniverseClosed Universe

Steady State Theory

Density


The Big Bang Theory

This theory states that the Universe is expanding due to a large ‘explosion’ (big bang) billions of years ago.

Evidence?

1. The Cosmic Microwave Background Radiation (CMB), which is thought to be an ‘echo’ of the initial explosion.

2. Hubble’s observations about red-shifted light.

There are different fates for the Universe with this theory:

1. The Universe expands for ever if there is not enough gravity to halt its expansion – OPEN UNIVERSE.

2. The Universe will eventually start to contract due to gravity – CLOSED UNIVERSE.


Steady State Theory

This theory states that the Universe is expanding and as it expands matter is created to maintain a uniform universal density of matter.

Evidence?

Hubble’s observations about red-shifted light.

However:

This theory has become less popular since the discovery of Cosmic Microwave Background Radiation (CMB).


Are we alone?

If there are aliens they would have

contacted us by now.

The Universe is so big, even if there are aliens,

they are too far away for us to ever meet them.

Life exists on Earth and only on Earth.

If there are aliens they will probably not look

like you or me.

For life to exist there must be liquid water, on a planet or moon

and oxygen.

You have 10 minutes!!!

We are all aliens, life began on comets and asteroids

and transferred to the Earth when they collided with it.

In pairs discuss the points below and then share you ideas with the rest of the group.


What is the name of the furthest planet from the Sun?

A. Earth

B. Jupiter

C. Pluto

D. Venus


Why is Venus hotter than Mercury?

A. It is closer to the Sun

B. It is further away from the Sun

C. Acid Rain

D. The Greenhouse Effect


What object from the Solar System is shown?

A. Comet

B. Planet

C. Asteroid

D. Moon


What elements is the Sun mostly made from?

A. Iron and nickel

B. Strontium

C. Hydrogen and helium

D. Helium and neon


Which of these planets has two moons called ‘Fear’ and ‘Dread’?

A. Earth

B. Venus

C. Saturn

D. Mars

© Boardworks Ltd 2003 KS4 Earth and Beyond. © Boardworks Ltd 2003 What we once thought…… I...

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Transcript of © Boardworks Ltd 2003 KS4 Earth and Beyond. © Boardworks Ltd 2003 What we once thought…… I...