7) Astronomy Flashcards

1
Q

What did the Sun form from?

A

A nebula

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2
Q

What is a nebula?

A

A cloud of dust and gas

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3
Q

What are the 4 stages of the Sun’s creation?

A

Cloud of gas and dust
Main sequence
Nuclear Fusion
Stable

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4
Q

What happens during the cloud of gas and dust phase?

A

Gas and dust collapses

Decrease in volume as pressure increases

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5
Q

What happens gravity pulls together nebulae?

A

A protostar forms

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6
Q

What happens in the main sequence?

A

Materials continue to collide until the temperature is high enough for hydrogen nuceli to fuse and form helium

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7
Q

What is the stable period during the main sequence called?

A

A main star sequence

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8
Q

What keep’s the Sun’s core hot?

A

Energy released from nuclear fusion

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9
Q

What is stable in the main sequence phase?

A

The outward energy released by nuclear fusion is balanced by the force of gravity pulling the Sun inwards

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10
Q

What is the life cycle of a star?

A

Main sequence
Red giant
White dwarf
Black dwarf

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11
Q

What happens during the main sequence of a star’s life cycle?

A

Hydrogen nuceli are fused together to form helium

This releases energy as heat and light

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12
Q

What happens during the red giant phase of a star’s life cycle?

A

All hydrogen fuel runs out
Star cools and expands (becoming a red giant)
Star fuses together helium nuclei to release energy

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13
Q

What happens during the white dwarf phase of a star’s life cycle?

A

Helium fuel runs out and star collapses inwards
Temperature increases
White dwarf forms

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14
Q

What is a white dwarf?

A

The hot core of a star

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15
Q

What happens during the black dwarf phase of a star’s life cycle?

A

Star completely cools and becomes a black dwarf

Black dwarf doesn’t emit any light or heat

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16
Q

What is the main sequence of a large star’s life cycle?

A

Red supergiant
Supernova
Black hole or neutron star

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17
Q

What happens during the red supergiant phase of a large star’s life cycle?

A

Nuclear fusion changes more of the star’s mass into energy

Star expands into supergiant

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18
Q

What happens during the supernova phase of a star’s lifecycle?

A

Largest stars explode in a supernova

Supernova produces elements heavier than iron and scatters them through the universe

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19
Q

What does a supernova leave behind?

A

Either a black hole or neutron star

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20
Q

What two processes rule the life cycle for stars?

A

Thermal expansion

Gravitational collapse

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21
Q

What happens if forces due to thermal expansion are larger than gravitational forces?

A

Star will expand

22
Q

What happens if forces due to gravity are larger than thermal expansion forces?

A

Star will shrink/ collapse

23
Q

What do all stars produce by fusion?

A

Hydrogen nuclei into helium in nuclear fusion

24
Q

What do large stars produce by fusion?

A

Hydrogen nuclei into lithium and other light metals

25
Q

What do supernova produce by fusion?

A

Enough energy for hydrogen nuclei to form elements heavier than iron

26
Q

How are all naturally occuring elements produced?

A

By nuclear fusion in stars

27
Q

What are the 2 theories about the origin of the Universe?

A

The Big Bang model

The Steady State model

28
Q

What is the Big Bang model?

A

All matter and energy in the universe compressed into a single point
This exploded and started to expand
Universe was extremely hot and dense
Universe is still expanding

29
Q

What age does the Big Bang model give to the universe?

A

14 billion years

30
Q

What is the Steady State model?

A

The Universe has alwasy existed this way and always will
As Universe expands new matter is created so density stays the same
Universe has no beginning or end

31
Q

What does the Steady State model not account for?

A

Cosmic microwave background (CMB)

32
Q

What does CMB stand for?

A

Cosmic microwave background

33
Q

What does the Doppler effect describe?

A

The phenomenon of the observed wavelength and frequency of waves changing when the source of the waves moves with respect to the observer

34
Q

What types of waves can the Doppler effect be experienced with?

A

All types of wave

35
Q

What happens to the frequency for observers when the source of waves approaches?

A

The frequency shifts upwards for observers

36
Q

What happens to the frequency for observers when the source of waves recedes?

A

The frequency shifts downwards for observers

37
Q

What is the red-shift effect?

A

Light from distant objects in space become shifted towards the red end of the spectrum

38
Q

What happens to the wavelength of light as an object moves away from us?

A

The wavelength of light emmited by the object gets longer

39
Q

Why does light get redder?

A

Red has the longest wavelength of the visible colours

40
Q

How does the speed of an object moving away from us affect how red it appears?

A

Faster moving object = longer wavelength = redder

41
Q

What is evidence for an expanding universe?

A

The further a galaxy from Earth, the greater the red-shift

Further away a galaxy is the faster it is moving away from us

42
Q

How does red-shift explain the Big Bang theory?

A

All objects in the universe are moving away from one another

Objects must have began from a single point

43
Q

How does red-shift explain the Steady State theory?

A

It states new matter is being created to account for the expanding Universe

44
Q

What radiation comes from every direction in the Universe?

A

Cosmic Microwave Background Radiation (CMBR)

45
Q

What produces CMB radiation?

A

Gas at very low temperatures

46
Q

What part of the EM spectrum is CMBR mostly in?

A

The microwave part

47
Q

What can CMBR be detected as?

A

Very low energy signals coming from all directions in space

48
Q

How can the Steady State model explain CMBR?

A

It cannot

49
Q

How is CMBR evidence for the Big Bang theory?

A

CMBR is considered to be the remnants of the explosion

50
Q

What can different types of telescope detect?

A

Different types of light

51
Q

What are problems for telescopes?

A

The Earth’s atmosphere absorbs many wavelengths of light

Light pollution can interfere with observations

52
Q

What are solutions to telescope problems?

A

Many telescopes are built away from civilisation

Some telescopes are sent into space