SpaceSeparate Physics

Space facts

Name ______________________________

Class ______________________________

Teacher ______________________________

1) There are eight planets and one dwarf planet (Pluto). 2) Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus,

Neptune. 3) A satellite is something in orbit around a planet. A

satellite can be natural (like the Moon) or artificial (like communications or weather satellites).

4) The solar system is part of the Milky Way galaxy. 5) A nebula is a cloud of dust and gas. 6) A nebula gets pulled together under gravity. Friction

heats hydrogen until the nebula is hot enough for nuclear fusion to happen.

7) When a star is formed it is stable because the forces within it are balanced. Gravity acts inwards. This is balanced by the outward force of radiation from nuclear fusion trying to make the star expand.

8) Nebula → Protostar → Main sequence star → Red giant → White dwarf → Black dwarf.

9) Nebula → Protostar → Main sequence star → Red super giant → supernova → neutron star/black hole

10) In the explosion of a massive star (supernova) elements heavier than iron are spread throughout the universe.

11) Gravity.

12) Velocity is a vector, whereas speed is a scalar. As a object orbits, its direction changes. Therefore the velocity changes even if speed does not.

13) If the speed increases, then the radius of an orbit decreases.

14) There is an observed increase in the wavelength of light from most distant galaxies. The further away the galaxies, the faster they are moving and the bigger the observed increase in wavelength. This effect is called the red-shift. Cosmic microwave background radiation (CMBR) is another piece of evidence.

15) The red shift tells us that the universe is expanding and that it began from a very small region that was extremely hot and dense.

16) The wavelength decreases as the source moves towards us (the Doppler effect). The opposite happens if the source is moving away from us.

17) Observations of supernovae suggest that distance galaxies are receding even faster.

1) How many planets are there in our solar system? (Hz) ×

2) Write the planets in the solar system in order.

3) What is a satellite? What are the two types of satellite?

4) What galaxy is the solar system a part of?5) What is a nebula?6) How is a star formed?

7) Once a star is formed, how does it reach equilibrium?

8) What are the stages in the life cycle of a star of similar size to the sun?

9) What are the stages in the life cycle of a star much more massive than the sun?

10) How are elements heavier than iron produced?

11) What provides the force that allows planets and satellites to maintain their circular orbits?

12) How can the force of gravity lead to changing velocity but unchanged speed.

13) What happens to the radius of an orbit if the speed increases?

14) What evidence do we have for the Big Bang?

15) What does the red shift tell us about the universe?

16) What happens to the wavelength of a wave if the source is moving towards us?

17) What have observations of recent supernovae suggested?

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Our solar system is made of one star (the Sun) plus eight planets (and a dwarf planet – Pluto) that orbit around the Sun.

The solar system is a small part of the Milky Way galaxy.

We can remember the order of the plants by using the following mnemonic:

My MercuryVery VenusEasy EarthMethod MarsJust JupiterSpeeds SaturnUp UranusNaming NeptunePlanets Pluto

A nebula is a cloud of dust and gas (helium and hydrogen) that gets pulled together under gravity.

Friction heats the gases until the nebula is hot enough for nuclear fusion to happen.

For this to happen, the core temperature has to be extremely high – in excess of 10 million degrees.

Nuclear fusion in a star like the Sun involves the combination of lighter isotopes of hydrogen to form helium, and the release of energy:

H+ H→ He+energy23

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Once these reactions have begun, the energy released maintains the temperature in the star, and fusion continues

Terrestrial planets

Gas giants

Dwarf planet

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until all the reactants have been used.Task: Complete in your exercise book

Basic

1. Name the eight planets in our solar system. 2. Complete the sentences. Choose the answers from the box.

There are eight planets in orbit around the Sun, along with some _________________ like Pluto. The solar system is part of the galaxy which is called the _________________.

The Sun was formed when a ___________________ (made of dust and gas) in space was pulled together by ________________. The force of ___________ caused these gases (mostly ____________ and helium) to heat until they were hot enough to generate its own energy through nuclear ______________.

Medium

1. Explain what is meant by nuclear fusion. 2. Name the: i) Four terrestrial planets ii) Two gas

giants iii) Three ice giants. 3. Explain why i) Venus is the hottest planet ii)

Neptune is the coldest planet. 4. Use the figure to the right to explain what happens to the mass of the Sun as hydrogen is converted to

helium. Why does this process release energy?

Hard

The energy radiated by a main sequence star like the Sun is released by a nuclear fusion reaction in its core.

Read the following information about this reaction then use it to answer the questions below.

• The net result of the nuclear fusion reaction is that four hydrogen nuclei produce one helium nucleus. There is a loss of mass of 0.7%.

• For nuclear fusion to occur nuclei must collide at very high speeds.

• The energy released during the reaction can be calculated as shown:

energy released [J] = loss of mass [kg] × (speed of light [m/s])2

(The speed of light is 3 × 108 m/s)

(a) Calculate the energy released when 1g of hydrogen fuses to form helium.(b) The table shows the lifetimes and surface temperatures of main

sequence stars with different masses. The higher the surface surface of a star, the higher the temperature and pressure in its core.

(i) Describe the relationship between the lifetime of a main sequence star and its mass.

(ii) Suggest an explanation for this relationship.

hydrogen dwarf planets Milky Way

nebula fusion friction

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(a)     There are eight planets in orbit around the Sun.

Which other type of object orbits the Sun?

Tick one box. 

Dwarf planet

Galaxy

Moon

Star

(1)

(b)     Complete the sentences.

Choose the answers from the box. 

black hole gravity friction

nebula protostar upthrust

The Sun was formed when a ____________________ in space was pulled

together by ____________________ .(2)

The table shows some data about the eight planets that orbit the Sun. 

PlanetDistance from

the Sun compared to the

Earth

Time to orbit the Sun in years

Mean surface temperature

in °C

Mercury 0.4 0.2 +125

Venus 0.7 0.6 +465

Earth 1.0 1.0 +22

Mars 1.5 1.9 –48

Jupiter X 12 –108

Saturn 9.6 30 –180

Uranus 19.3 84 –216

Neptune 30.0 165 –201

(c)     What pattern links the distance a planet is from the Sun and the time taken by the planet to orbit the Sun?

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________(1)

(d)     Estimate the value of X in the table.

Distance = ____________________(1)

(e)      A student looked at the data in the table and wrote the following conclusion:

‘The mean surface temperature of a planet decreases thefurther the planet is from the Sun.'

Explain why this conclusion is not totally correct.

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___________________________________________________________________(3)

(Total 9 marks)

When a star is formed it is stable because the forces within it are balanced.

Gravity acts inwards. This is balanced by the outward force of the radiation from nuclear fusion trying to make the star expand.

The life cycle of a star depends on the initial mass of the star. For a star of similar size to our Sun, once hydogen starts to run out the force of fusion decreases and the star therefore contracts. This increases the temperature of the core until helium starts fusing. The increases the radiative force of force and so the star expands to form a red giant.

Following this stage, the outer layers drift out into space as a planetary nebula, and leaving behind a hot and dense white dwarf. Over time, this then cools to form a black dwarf.

Stars which are much more massive than the Sun form a red supergiant. Heavier and heavier elements start to fuse, until a massive explosion called a supernova occurs. What then happens depends on the mass of the star. Elements heavier than iron are produced in this supernova and this spreads out these elements throughout the universe.

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What happens next then depends on the mass of the star. The most massive stars form a black hole, whose gravitational force is so strong that not even light can escape.

Less massive stars leave behind a hot dense star called a neutron star.

Task: Fill in the blanks below.

Q1.

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Astronomers claim that there are about 300 billion stars in the Milky Way.

(a)     Describe how stars are formed.

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(b)     Use the correct answer from the box to complete the sentence. 

decay fission fusion

Energy is released in stars by the process of nuclear _________________ .(1)

(c)     State why a star is stable during the ‘main sequence’ period of its life cycle.

___________________________________________________________________

___________________________________________________________________(1)

(d)     The life cycle of a star after the ‘main sequence’ period depends on the size of the star.

A particular star is the same size as the Sun.

What are the stages, after the main sequence, in the life cycle of this star?

State them in order by writing in the boxes.

 (3)

(Total 8 marks)

Q2.

The early Universe contained only the lightest element.

(a)     Use the correct answer from the box to complete the sentence. 

hydrogen iron uranium

The early Universe contained only _______________________ .(1)

(b)     Use the correct answer from the box to complete the sentence. 

main sequence star protostar supernova

The heaviest elements are formed only in a ________________________ .(1)

(c)     Use the correct answer from the box to complete the sentence. 

red giant red super giant white dwarf

Only a star much bigger than the Sun can become a __________________ .(1)

(d)     The Universe now contains a large variety of different elements.

Describe how this happened.

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(Total 7 marks)

A satellite is something in orbit around a planet.

They can be natural (like the Moon) or artificial (like communications or weather satellites).

Geostationary satellites orbit the Earth once every 24 hours. They are used for communications.

Monitoring satellites (for weather) are lower and orbit every 2-3 hours.

Satellites orbit around planets in circular (or slightly elliptical) orbits. For circular orbits, the force of gravity can lead to a changing velocity but unchanged speed. This is because the direction of the satellite changes. As velocity is a vector (consisting of both size and direction) then the velocity must also change.

We can calculate the distance travelled by the circumference of the orbit.

Example question: Copy the model answer out in the space below.

A geostationary satellite orbits the Earth once every 24 hours. If the radius of orbit is 42,371 km, what is the speed of the satellite (in m/s)?

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Basic

1. What is the name of the force that keeps a satellite in orbit around a planet?

2. What are the two types of satellite that orbit the Earth?

3. Name two uses of man-made satellites.

4. Some satellites are put into orbit close to Earth and some are further away. What impact does this have on:

a) orbit speed. b) orbit time?

Medium

5. What is a geostationary satellite? How often does it orbit the Earth?

6. Most satellites orbit the Earth in a squashed circle called an ellipse. Comets orbit the Sun in a very extreme

elliptical orbit. Look at the diagram below and answer the following questions.

a) Mark on the diagram the place on its orbit where the comet will be traveling fastest.

b) Why do you think it will be traveling fastest at this point?

c) Mark on the diagram the place on its orbit where the comet will be traveling slowest?

d) Why do you think it will be traveling slowest at this point?

7. When in stable orbit, a satellite travels at a constant speed but its velocity is constantly changing. Why is

this?

8. Which of the satellites (L or M):

a) Is a geostationary satellite?

b) Is used as a monitoring satellite?

c) Takes 24 hours to complete its orbit?

Hard

9. If a geostationary satellite orbits 36,000 km above the

surface of the Earth and the radius of Earth is 6,371 km, what is the speed of a geostationary satellite?

10. Light from the Sun takes about 3 minutes to reach Mercury, about 8 minutes to reach the Earth, Jupiter

takes about 11 years to orbit the Sun, whereas Mercury takes about 3 months. Which of the three planets

travels a) the slowest? b) the fastest? Explain your reasoning.

Orbit of comet

The Sun

Q1. The figure below shows what scientists over 1000 years ago thought the solar system was like.

 

(a)     Give one way that the historical model of the solar system shown in the figure above is different from what we now know about the solar system.

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______________________________________(1)

(b)     Give one way that the solar system shown in the figure above is the same as what we now know about the solar system. (1)

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(c)     The first artificial satellite to orbit the Earth was launched into space in 1957.

Describe the orbit of an artificial satellite. (1)

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(d)     What provides the force needed to keep a satellite in its orbit? (1)

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(e)     All stars go through a lifecycle.

The star Mira will go through a supernova stage in its lifecycle but the Sun will not.

How is the star Mira different to the Sun? (1)

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Q2. Man-made satellites can orbit the Earth, as shown in the figure below.

 

The satellite experiences a resultant force directed towards the centre of the orbit.

The resultant force is called the centripetal force

(a)     What provides the centripetal force on the satellite?

___________________________________(1)

(b)     State two factors that determine the size of the centripetal force on the satellite. (2)

1. _________________________________________________________________

2. _________________________________________________________________

(c)     The table below gives data for five different satellites orbiting the Earth. 

SatelliteAverage height above Earth’s

surface in kilometres

Time taken to orbit Earth once

in minutesMass of satellite

in kilograms

A     370   93 419 000

B     697   99        280

C     827  103        630

D   5 900  228        400

E 35 800 1440     2 030

(i)      State the relationship, if any, between the height of the satellite above the Earth’s surface and the time taken for the satellite to orbit the Earth once. (1)

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(ii)     State the relationship, if any, between the time taken for the satellite to orbit the Earth once and the satellite’s mass. (1)

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(d)     Over 300 years ago, the famous scientist Isaac Newton proposed, with a ‘thought experiment’, the idea of satellites.

Newton suggested that if an object was fired at the right speed from the top of a high mountain, it would circle the Earth.

Why did many people accept Isaac Newton’s idea as being possible?

Tick (✓) one box. (1)

Isaac Newton was a respected scientist who had made new discoveries before.

Isaac Newton went to university.

It was a new idea that nobody else had thought of before.

Thousands of satellites are now in orbit around the Earth. A student used the internet to collect information about some of them.

Basic: Using the data in the table, calculate the circumference of the orbits of all the satellites:

1) The Moon2) GEO3) Navstar4) Lageos5) HST6) ISS

Medium: Using your answers to the basic questions, calculate the speeds of the satellites. Remember to convert the time into seconds! The first one has been done for you.

1) GEO2) Navstar3) Lageos4) HST5) ISS6) What conclusion on the relationship between the average distance and speed can

the student come to on the basis of the data in the table?7) Explain this relationship in terms of the force of gravity.

Hard: This question will really make you think! You will need to rearrange this equation for speed. Be careful to convert units!

The Earth is orbiting around the Sun at an incredible speed of 107,000 km/h! Given that the Earth takes 365 days to orbit around the Sun, calculate the distance from the Earth to the Sun!

km → m × 1000

mins → s × 60hours → mins × 60days → hours × 24

Name of satellite

Average distance from

the centre of the Earth in

kilometres

Speed in metres per second

Time taken to orbit the Earth

The Moon 391 400 1017 28 days

GEO 42 200 1 day

Navstar 26 600 12 hours

Lageos 12 300 3.8 hours

HST 7 000 97 mins

ISS 6 700 92 mins

The Big Bang theory suggests that the universe began from a very small region that was very hot and dense. It then exploded outwards to form the Universe.

There are two pieces of evidence for this:

1) Red shifted light from far away galaxies.

2) Cosmic microwave background radiation

When a police car drives past you, its siren sounds higher pitched as it approaches, and lower pitched as it moves away. This is the Doppler effect.

The same thing happens to the light emitted by very fast moving objects, such as distant stars, and can be seen in their spectra. This is red shift. The wavelength of light from the most far away galaxies is increased (but the frequency is decreased). This is the main evidence for the Big Bang as it shows the Universe is expanding.

If a galaxy is moving towards ours, then the light from that galaxy is blue-shifted. This means that the wavelength is reduced, but the frequency is increased.

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Task: Complete in your exercise book.

Basic

1. What happens to the light a galaxy gives off if the galaxy is moving away from us?2. What was the Big Bang?3. What is happening to the size of the Universe?4. What evidence do we have for the big bang?5. Galaxy X has a larger red-shift than Galaxy Y. Which galaxy, X or Y is….

a) Nearer to us. b) Moving away faster.

6. What happens to the light a galaxy gives off if the galaxy is moving towards us?

MediumBy measuring the red-shift. Hubble was able to calculate the speed at which the galaxies are moving away from the Earth. He was also able to calculate the distance of these galaxies from the Earth. The graph shows some of the data calculated by Hubble. 1. What relationship between the speed of a

galaxy and the distance is suggested by Hubble’s results?

2. The data from the two galaxies, M and N has been included in the graph. The light from galaxy M has a smaller red-shift than the light from galaxy N. What does the difference in red-shift tell scientists about the two galaxies, M and N?

3. The gradient of the line drawn on the graph gives a number known as the Hubble constant. The Hubble constant can be used to estimate when the universe began. Use the graph to calculate the value of the Hubble constant (in units of km/s per megaparsec).

HardAstronomers use red shift in two ways. They calculate the distance to each galaxy from Earth. They also calculate the speed at which galaxies are moving away from Earth. The table shows some results. Distance is given in zettametres (Zm). One zettametre is 1021 metres.

1. Complete the data for time in the table.

2. Explain how the data for time provides evidence for the theory that the origin of the Universe was a huge explosion (“Big Bang”).

Q1. Light is given out by the Sun and a distant galaxy.

(a)     Compared to the light from the Sun, the light from the distant galaxy has moved towards the red end of the spectrum.

(i)      What name is given to this effect? (1)

______________________________________________________________

(ii)     Complete the following sentence by drawing a ring around the line in the box that is correct. (1)

The fact that light from a distant galaxy seems to move towards the red end of the spectrum gives scientists evidence that

 

(b)     Scientists have a theory that the universe began from a very small point and then exploded outwards.

(i)      What name is given to this theory? (1)

______________________________________________________________

(ii)     Which statement gives a reason why scientists think that the universe began with an explosion?

Put a tick ( ) in the box next to your choice. (1) 

At the moment it is the best way of explaining our scientific knowledge.

It can be proved using equations.

People felt the explosion.

Q2. Scientists can use the visible light spectrum from distant stars to determine whether the stars are moving.

The visible light spectrum from stars includes dark lines at specific wavelengths.

(a)     The diagram shows the visible light spectrum from the Sun and from four other stars, A, B, C and D.

  

(i) Which star, A, B, C or D, is moving away from the Earth?

(1)

(ii)     How does the speed of star B compare with the speed of star D?

Tick ( ) one box. 

Tick ( )

The speed of star B is greater than the speed of star D.

The speed of star B is less than the speed of star D.

The speed of star B is the same as the speed of star D.

(1)