The Solar System

Question 1

What is the geocentric model of the Solar System?

Answer 1

Put the Earth in the centre of everything with the planets and the Sun orbiting around it

Question 2

What is the heliocentric model of the Solar System?

Answer 2

The Sun at the centre of the Solar System

Question 3

What are asteroids?

Answer 3

Compromised of rock and metal and are smaller than planets, most of which are found between the orbits of Mars and Jupiter

Question 4

What are comets?

Answer 4

Frozen leftovers from the formation of the Solar System composed of dust, rock and ice that orbit the Sun

Question 5

What is an elliptical orbit?

Answer 5

The orbit of an object around another in an oval-shaped path, such as the orbit of planets around the Sun in our Solar System

Question 6

Give an example of a natural satellite

Answer 6

Moon

Question 7

Why do telescopes in orbit around the Earth give much clearer images than ground-based telescopes?

Answer 7

Clouds and dust in the air do not interfere with the image

Question 8

Why must telescopes that are used to detect different types of EM waves be placed in orbit?

Answer 8

Because the atmosphere absorbs some of the radiation they are designed to detect

Question 9

What is weight?

Answer 9

The force of gravity acting on matter

Question 10

What does weight depend on?

Answer 10

Mass and GFS

Question 11

What are artificial satellites used for?

Answer 11

Communications and observation of the Earth and space

Question 12

Why does an orbiting body constantly change velocity?

Answer 12

In a circular orbit, it has a constant speed as it travels, but its direction is constantly changing

Question 13

For a satellite, how does the force change its direction but not its speed?

Answer 13

The gravitational force between the Earth and the satellite is at right angles to the direction of movement (centripetal force)

Question 14

What is a nebula?

Answer 14

A cloud of dust and gases (mainly hydrogen)

Question 15

What is the life cycle of an average star?

Answer 15

• Stellar nebula (cloud of gas)
• Average star
• Red giant
• Planetary nebula
• White dwarf

Question 16

What is the life cycle of a massive star?

Answer 16

• Stellar nebula (cloud of gas)
• Massive star
• Red supergiant
• Supernova
• Black hole or neutron star

Question 17

Describe the formation of a star

Answer 17

• Nebula’s materials pulled together by their own gravity
• Clouds contract and become denser
• Hydrogen heats up and spirals inwards and may start to glow
• As more mass is attracted, cloud’s gravitational pull strengthens and heats the material even more, which becomes a protostar
• Temperatures and pressures in centre of protostar become high enough to force hydrogen nuclei to fuse together and form helium (fusion reaction releases a lot of energy as EM radiation)
• Outward pressure from hot gases balances the compression due to gravity
• Star now in the main sequence part of its life-cycle

Question 18

What is the Doppler effect?

Answer 18

The apparent difference between the frequency at which sound/light waves leave a source and that at which they reach the observer

Question 19

Give an example of the Doppler effect

Answer 19

As an ambulance siren travels away from you, its pitch gets lower

Question 20

What happens to the sound waves behind a moving sound source?

Answer 20

They become ‘stretched’, which makes their wavelength longer; this in turn lowers their frequency and so we hear the sound as a lower pitch

Question 21

What happens if you are travelling in a car with the same velocity as the vehicle with the siren in terms of the Doppler effect?

Answer 21

The sound would not appear to change

Question 22

What is the red shift?

Answer 22

When the wavelength of light is ‘stretched’, the light is seen as shifting towards the red part of the spectrum (happens when a star is moving away from us)

Question 23

What is the red shift a measure of?

Answer 23

How far along the spectrum lines have moved

Question 24

What happens to the wavelength of light waves when a star is moving towards us?

Answer 24

The waves become shorter and the frequency increases, so the pattern of lines moves towards the blue end of the spectrum

Question 25

What does it mean when the further the lines are shifted in the visible spectrum of light?

Answer 25

The faster the star is moving relative to us

Question 26

What is the relationship between a galaxy, its red shift and its distance from us?

Answer 26

The further away a galaxy is, the greater its red-shift and so the faster it is moving away from us

Question 27

What caused matter to clump together to form stars as the Universe expanded during the early stages after the Big Bang?

Answer 27

Gravity

Question 28

What does the Steady State theory suggest?

Answer 28

The Universe has always existed and is expanding; new matter is continuously created within the Universe as it expands

Question 29

What does the Big Bang theory suggest about radiation?

Answer 29

Huge amounts of radiation were released at the beginning of the Universe

Question 30

What is happening to the radiation released from the Big Bang as the Universe expands?

Answer 30

The wavelength of this radiation has increased and so now it is only detectable as microwave radiation

Question 31

What is cosmic microwave background (CMB) radiation?

Answer 31

The radiation from the beginning of the Universe whose wavelength has increased as the Universe expanded to only be detected as microwave radiation

Question 32

What do the Big Bang and Steady State theories have in common?

Answer 32

Both say that the Universe is expanding

Question 33

What can be used as support for the Big Bang and Steady State theories?

Answer 33

Observations of red-shift in the light from other galaxies

Question 34

What does CMB radiation provide evidence for?

Answer 34

The Big Bang theory only, as the Steady State theory cannot explain the CMB radiation

Question 35

Which theory for the Universe is accepted by most astronomers today?

Answer 35

The Big Bang theory, as there is more supporting evidence for it