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Physics > Unit 7 - Astronomy > Flashcards

Unit 7 - Astronomy Flashcards

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1
Q

What was Ptolemy’s idea?

A

That Earth was in the centre and everything orbited it (geocentric model)

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2
Q

What was Copernicus’ idea?

A

That the sun was at the centre of the solar system (heliocentric model)

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3
Q

What are comets mostly made from

A

Ice

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4
Q

What does our current solar system model show?

A

8 planets, 5 dwarf planets, thousands of comets and millions of asteroids

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5
Q

What did the invention of photography allow astronomers

A

To make more detailed observations and measurements

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6
Q

What are computers used for by astronomers

A

To analyse the information from telescopes

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7
Q

Why do telescopes in orbit give clearer images?

A

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

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8
Q

Why must telescopes deleting certain electromagnetic waves be places in orbit

A

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

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9
Q

What is weight

A

The force of gravity acting on you

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10
Q

What is the word equation for weight

A

Weight = mass x gfs

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11
Q

What makes surface gravity greater

A

A larger mass but smaller radius (denser)

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12
Q

What are artificial satellites used for

A

Communications and to observe the earth

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13
Q

Give 3 uses of satellites

A

Weather
Broadcasting
Photographs

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14
Q

What are the 3 types of orbits satellites can be put into

A 
Geostationary (over the same point
Polar orbit (over the Poles)
Low earth
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15
Q

Why does an orbiting body have a constantly changing velocity

A

The direction is changing

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16
Q

Is the gravitational force Ona satellite in low orbit strong or weak

A

Strong

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17
Q

What will happen to the earth when our sun becomes a red giant?

A

It will get swallowed up

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18
Q

What is a nebula?

A

A cloud of dust and gases (mainly hydrogen)

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19
Q

How is a protostar formed from a nebula?

A

The material is pulled together by its own gravity, the hydrogen becomes hotter and starts to glow, as more mass is pulled, the gravity gets stronger and it gets hotter.

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20
Q

What happens during the main sequence of a star

A

The high pressures force the hydrogen nuclei to fuse spit form helium. Fusion reactions release a lot of energy.

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21
Q

What form of energy is released from fusion?

A

Electromagnetic radiation

22
Q

What stops the start in main sequence from collapsing in on itself

A

The pressure from the hot gases balance the compression of gravity

23
Q

How does a start become a red giant?

A

When most of the hydrogen has fused into helium, the core is not hot enough to withstand the gravity and collapses, th per outer layer expands to form the red giant

24
Q

What stage is our current star in?

A

Main sequence

25
Q

How long does a star remain a red giant

A

1 billion years

26
Q

How is a white dwarf formed?

A

Fusion continues forming heavier elements, the star throws of a shell of gas and the rest of the star is pulled together by gravity and collapses to form a white dwarf.

27
Q

How does a white dwarf become a black dwarf

A

No fusion happens so the star begins to cool.

28
Q

What is the life cycle of stars like ours (6)

A

Nebula, protostar, main sequence, red giant, shell of gas, white dwarf

29
Q

How is a red supergiant formed

A

If there is more mass, fusion of hydrogen happens much quicker

30
Q

How does a supernova occur?

A

At the end of a red supergiant, it rapidly starts to co,,also and then explodes

31
Q

How is a black hole formed

A

If the mass of the star is 4 times our star, gravity pulled the remains together, light cannot escape from the pull of gravity

32
Q

How is a neutron start formed

A

If the star isn’t massive enough, gravity pulls it together to form a small, very dense star

33
Q

What is the life cycle of a massive star? (6)

A

Nebula, protostar, main sequence, red supergiant, supernova, blackhole/ neutron star.

34
Q

What is the Doppler effect

A

When the pitch of sounds change due to moving or becoming closer to you

35
Q

How does the Doppler effect occur?

A

The sound waves behind the source become ‘stretched’ making the wavelength longer and the frequency lower so the pitch is lower. It is opposite if you are in front of the sound source

36
Q

What must be happening for the Doppler effect to take place

A

If the observer is stationary

37
Q

What is red-shift

A

When the patterns of the dark lines on a visible spectrum have been shifted to the red end of the spectrum due to the object moving away

38
Q

When does red - shift occur

A

When an object is travelling further away from the observer

39
Q

When does blue - shift occur?

A

When the object is moving closer to the observer

40
Q

What does red-shift show about the universe

A

That it is expanding

41
Q

Describe the speed of a large red-shift

A

Faster

42
Q

What does the Big Band theory explain about the origin of the universe?

A

All matter started as a tiny point of concentrated energy, the universe expanded from this point and is still expanding, the gravity clumped matter to form stars

43
Q

How is matter dispersed according to the Big Bang theory as it expands

A

Spreading away as it expands

44
Q

What does the Steady State theory say

A

The universe has always existed, it is expanding

45
Q

What is the main difference between the Steady State theory and the Big Bang theory

A

The BBt says matter is not created, the SSt theory says matter is created

46
Q

Why is the energy released form the Big Band theory only detected as microwave radiation

A

The universe is expanding so the wavelengths are increasing

47
Q

What is cosmic microwave background radiation?

A

The radiation that is detected from the universe

48
Q

How was cosmic microwave background radiation discovered?

A

2 radio astronomers detected the microwave signals, thought it was a fault in their equipment but realised that they were real.

49
Q

What evidence supports both the SSt and the BBt?

A

The universe is expanding due to red-shift

50
Q

Why is the Big Bang theory preferred over the Steady State theory?

A

It can support the evidence of the CMB radiation

Physics (12 decks)

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