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GCSE Physics > P16 - Space > Flashcards

P16 - Space Flashcards

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1
Q

How did The Solar System form?

A

The Solar System formed from gas and dust that gradually became more concentrated due to the gravitational attraction that pulled it all together.

*Solar = related to the sun

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2
Q

What is the most central and important part of The Solar System?

A

The Sun - located at the centre of the Solar System.

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3
Q

How did the Sun form?

A

Billions of years ago, the sun was formed from the dust and gas pulled together by gravitational attraction.

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4
Q

What % of the Solar System’s mass in the Sun?

A

98.6%

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5
Q

What is the Sun an example of?

A

A star

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6
Q

What is a star?

A

A star is a self-luminous hot ball of plasma.

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7
Q

What is plasma - 4th state of matter?

A

Superheated matter - so hot that electrons rip away from the atoms forming ionised gas.

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8
Q

Why are stars self-luminous and why do they generate heat?

A

Stars undergo nuclear fusion which creates both light and heat energy.

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9
Q

What 2 elements is the Sun made up of?

A

Hydrogen and Helium

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10
Q

What is the fuel used by the sun in nuclear fusion?

A

Hydrogen is the fuel.

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11
Q

What is the product of nuclear fusion used by the sun?

A

Helium (+ light and heat)

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12
Q

How do all stars begin to form?

A

All stars begin to form when clouds of dust and gas merge together and become more and more concentrated.

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13
Q

What is a star-to-be called?

A

A protostar

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14
Q

How does a protostar turn into a star?

A

1) The protostar gets denser and its particles speed up - increasing the temperature.
2) Energy is transferred from the gravitational potential energy store to the thermal store.
3) Eventually, the nuclei of hydrogen atoms fuse together, forming helium nuclei.

A star is born!

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15
Q

What is a planet?

A

A *celestial body that orbits a star.

*celestial body = positioned in outer space

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16
Q

How do planets differ from stars and why do they not become stars?

A

Planets are protostars that didn’t have enough mass to fuse hydrogen into helium.

E.g Jupiter was close to being a star

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17
Q

What are the 8 planets our Solar System in order of the closest to the sun first?

A

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune

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18
Q

What are the first 4 and last 4 planets grouped as?

A

First 4 = rocky planets

Last 4 = gas giants

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19
Q

Why is earth habitable?

A

Earth is the third planet from the sun.

It lies in the zone where the temperature is between 0°C and 100°C - therefore liquid water can exist.

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20
Q

What is the heaviest known natural element? What is its half life?

A

Uranium - its half life is 4500 million years.

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21
Q

What is the presence of Uranium on earth evidence for?

A

It is evidence that the Solar System formed from the remnants of a supernova (explosion at the end of a star’s life cycle).

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22
Q

What are dwarf planets?

A

A smaller celestial, planetry body that is in direct orbit of the sun.

E.g Pluto declared a dwarf planet in 2006

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23
Q

What is a moon?

A

A moon is a natural satellite of a planet.

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24
Q

What does our moon do for earth?

A

It makes earth more liveable - by moderating its ‘wobble’ on its axis - and causing tides.

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25
Q

What is a meteoroid?

A

A meteor is a small rocky/metallic piece of debris that is not yet visible in the atmosphere.

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26
Q

What are meteoroids called when they become visible? What is their nickname?

A

Meteors

Nickname: Shooting stars (not actually stars)

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27
Q

Why does a meteor glow (whence becoming visible)?

A

It glows because as it enters the earth’s atmosphere, it heats up due to friction with the air, causing gases around the meteor to glow.

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28
Q

How do the colours of different meteor’s glows vary?

A

Colours depend on the chemicals present.

E.g Calcium = Purple

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29
Q

What is a meteorite?

A

A meteorite is a meteoroid that has entered the earth’s atmosphere as a meteor and hit the earth’s surface.

Meteorite = landed

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30
Q

What is a Comet?

A

A comet is a frozen body of rock that orbits the sun in an elliptical (squashed circle) shape.

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31
Q

How do comets and meteoroids differ?

A

Comets are massive icy body’s that orbit the sun, whereas meteoroids are small rocky/metal objects that DON’T ORBIT the Sun.

Debris from comets often become meteoroids.

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32
Q

What is the tail of a comet?

A

Sublimated ice and dust.

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33
Q

What causes a comet to be colourful?

A

Seasonal cycles of ice and dust cause different colour changes depending on where the comet is in its orbit.

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34
Q

What is a nebula?

A

A giant cloud of dust and gas which form pretty colours and patterns.

E.g Orion Nebula is just one of many nebulae.

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35
Q

What is an Asteroid?

A

Small rocky objects that orbit the sun.

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36
Q

What is the Asteroid Belt?

A

The region in the Solar System between the orbits of Mars and Jupiter where asteroids orbit the sun.

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37
Q

What galaxy are we (our Solar System) in?

A

The Milky Way

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38
Q

What does our entire Solar System orbit? How many stars are in the Milky Way (our Galaxy)?

A

A black hole at the centre of the Milky Way galaxy.

There are about 100 thousand million stars in the Milky Way.

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39
Q

What are main sequence stars? What does the fusion taking place in stars produce?

A

Stars going through the main stage of their life where they radiate energy due to the fusion of hydrogen nuclei.

-Fusion processes in stars produce all of the naturally occuring elements (92).

40
Q

How many years can main sequence stars maintain their energy output?

A

Millions of years

41
Q

What maintains the stability of a star?

A

The inward and outward forces being at equilibrium.

Inward = Gravity pushing
Outward = Radiation from Fusion
42
Q

What happens when there are no more hydrogen nuclei to fuse?

A

The star is destabilised and will eventually collapse due to the force of gravity not being balanced.

43
Q

What are the colours of a star in order of hottest to coldest?

A

1) Blue
2) Blue-white
3) White
4 Yellow
5) Orange
6) Red
7) Black

*Think bunsen burner

44
Q

What colour is our star (the Sun)?

A

White-Yellow.

*Even though it appears orange.

45
Q

Why is the colour of a star important for stability?

A

The hot stars can often burn themselves out (e.g Blue, Blue-white stars).

Our Sun is the perfect temperature for the stability of life.

46
Q

What does the cycle of the star after its main sequence stage depend on?

A

The size of the star - whether its bigger or smaller than our Sun.

47
Q

What happens to the core and outer layer of a star when a star, SMALLER than (or the SAME size as) the Sun, dies?

A

Its core collapses.

Its outer layer swells out, cools and turns red.

48
Q

What is a small star called when it turns red after dying?

A

A Red Giant

49
Q

What does a small star turn into after it becomes a red giant?

A

The star collapses and becomes hot again - a white dwarf.

50
Q

What do small stars do when they finally fade out after becoming a white dwarf?

A

Black dwarfs - they go cold.

51
Q

What happens to the core and outer layer of a star when a star, BIGGER than the Sun, dies?

A

The core collapses.

The outer layer swells out and cools to become a Red Supergiant.

52
Q

What occurs when the matter of a red supergiant starts to collapse?

A

The matter is compressed.

53
Q

What happens when the compression is suddenly reversed?

A

A cataclysmic explosion called a supernova.

54
Q

What does a supernova do? How long can a supernova outshine an entire galaxy?

A

A supernova produces all of the elements HEAVIER THAN IRON and distributes them throughout the universe.

A supernova can outshine a galaxy for several weeks.

55
Q

What does a supernova compress the core of a star into?

A

A neutron star - extremely dense made up of only neutrons.

56
Q

What can a supernova become if the star is massive enough?

A

A black hole

57
Q

Why can nothing escape a black hole?

A

The gravitational field of a black hole is too strong.

Not even light or any other electromagnetic radiation can escape it.

58
Q

What is a satellite?

A

A body that orbits a much bigger body.

59
Q

What are the 2 types of satellite? What is an example for each?

A

Natural - The Moon

Artificial - International Space Station (ISS)

60
Q

What does the earth orbit?

A

The Sun

61
Q

What force acts on the orbiting body?

A

A gravitational force between the body and the centre of the larger body.

62
Q

What is the name given for the type of force that enables orbit?

A

Centripetal force

63
Q

What is Centripetal force? Give 2 examples

A

The force that keeps something moving in circular motion.

E.g:

  • gravity - planets orbiting
  • tension - swinging a yoyo around
64
Q

How does Centripetal force link to satellites and orbit?

A

A planet is kept in orbit by the centripetal force of gravity.

65
Q

What direction does centripetal force always act in?

A

Towards the centre of a gravitational field (inwards).

66
Q

Why is the centripetal force said to be the resultant force acting on a planet or satellite on orbit?

A

Because no other forces act on it.

67
Q

Where is the direction of the velocity of a planet in relation to the circular orbit?

A

The direction of velocity is at right angles (use a tangent) to the direction of the centripetal force of gravity.

68
Q

Why is a planet said to experience acceleration towards the centre of the circle?

A

Acceleration is about change in velocity.

Velocity is a vector (magnitude and direction). Since the direction is always changing in orbit, the planet is said to accelerate towards the centre of the circle.

69
Q

Why does the magnitude of the velocity (speed) of a planet not change when in orbit?

A

Although the direction of the velocity changes - causing acceleration towards the centre of the circular orbit - because the force is at right angles to the direction of velocity, no work is done.

So, the speed of the orbit does not change.

70
Q

What 2 things must a satellite be to maintain a steady orbit after launch?

A

1) Must be above the Earth’s atmosphere.
- Too low = falls to the surface because of atmospheric drag.

2) Must be launched at the correct, particular speed.
- Too fast = launch off into space.
- Too slow = falls to the surface.

71
Q

How are satellites used - 4 ways?

A

1) Weather Monitoring
2) Military Surveillance (spying)
3) Communications:
(phone —> tower —> satellite —> tower —> phone)
4) GPS (Global Positioning System)

72
Q

What are 3 examples of different types of orbit?

A

1) Geostationary orbit (used in GPS) - satellite’s orbital period = earth’s rotational period of 24 hours - therefore, the same area of the earth can be observed
2) Low Earth orbit - relatively close to the earth’s surface
3) Elliptical orbit - orbits in an oval shape

  • Rule:
  • Close satellite = small radius = slow (*time) = monitoring
  • Far satellite = large radius = fast (*time) = geostationary orbit

*fast and slow in terms of time (not orbital speed).

73
Q

What is the relationship bewteen the height of a satellite and its orbital speed? Why?

A

Higher satellite = slower

The closer the too body’s are, the stronger the centripetal force of gravity is.

74
Q

How can you tell how far away a star or galaxy is?

A

By looking at the light waves.

75
Q

What is red-shift?

A

An example of the *doppler effect - when the light source (star or galaxy) is moving away from us.

The spectrum of light is shifted towards the red part of the spectrum.

Remember colours:
ROYGBIV

*see last flashcard

76
Q

How can you tell when red-shift is occuring and a star or galaxy is moving away?

A

Red-shift means light moves to the Red part of the spectrum. So:

-Light shifts to Longer wavelengths & Lower frequencies.

(*Robert Lewandowski)

77
Q

What is blue-shift?

A

An example of the doppler effect - When the light source (star or galaxy) is moving towards us.

The spectrum of light is shifted towards the blue part of the spectrum.

78
Q

How can you tell when blue-shift is occuring and a star or galaxy is moving towards us?

A

Blue-shift means light moves to the blue part of the spectrum. So:

-Light shifts to shorter wavelengths & higher frequencies.

79
Q

What does red-shift & blue-shift look like on a spectrum diagram?

A

Red-shift - the pattern of absorption lines shift to the red part of the spectrum.

Blue-shift - the pattern of absorption lines shift to the blue part of the spectrum.

pattern of absorption lines = spectral lines

80
Q

How does the rate of red-shift or blue-shift indicate the speed of the star/galaxy?

A

The faster a star or galaxy is moving (away or towards), the bigger the shift is.

Greater shift = Greater speed

81
Q

How does the distance a galaxy is away from us indicate the size of its red-shift?

A

The further away a galaxy, the bigger its red-shift.

*discovered by astronomer Edwin Hubble

82
Q

Why is the universe said to be expanding?

A

All the distant galaxies are moving away from each other - the whole universe is expanding.

83
Q

What theory was put forward to explain the beginning of the universe and its constant expansion?

A

The Big Bang Theory

84
Q

What 2 things does the Big Bang Theory state?

A

1) The universe is expanding after exploding suddenly from a very small, and extremely dense and hot region 13 billion years ago (The Big Bang).
2) Space, time and matter were created in the Big Bang.

85
Q

What are the 3 justifications for the theory?

A

1) Existence of Cosmic Microwave Background Radiation (CMBR)
2) Red-shift - universe is constanly expanding
3) Primordial (very start) Hydrogen/Helium

86
Q

Why is the existence of CMBR a justification for the Big Bang Theory?

A

CMBR was originally high energy gamma radiaton just after the Big Bang, and has been travelling through space since then.

As the universe has expanded, it has stretched out (longer wavelength) into microwave radiation.

CMBR is what light was when it first existed - it cannot be explained without the Big Bang Theory.

87
Q

What do scientist believe about the mass of stars in a galaxy?

A

Stars account for 98.6% of mass in a Solar System.

Therefore, they believe that if the mass of stars was the only mass in the galaxy, galaxies should be spinning a lot faster.

They believe that there is missing mass that can’t be seen.

88
Q

What is dark matter?

A

The missing mass of galaxies and the universe that can’t be seen.

89
Q

What is dark matter doing to the overall universe?

A

Dark matter is increasing the overall density of the universe.

90
Q

What do scientists believe about the nature of the universe’s expansion?

A

They believe the expansion of the universe is accelerating.

91
Q

What is causing the acceleration of the universe’s expansion? Why?

A

Dark energy - the force of gravity CANNOT explain this acceleration and dark energy.

92
Q

What are the 2 possibilities for the universe?

A

1) ‘Big Yawn’ - universe keeps expandings forever until all the stars die out.
2) ‘Big Crunch’ - universe stops expanding and goes into reverse, causing a big ‘crunch’.

93
Q

How could the Big Yawn happen?

A

The density of the universe (without dark matter) would have to be LESS than a certain amount.

Dark energy would not be limited and would keep accelerating the expansion of the universe.

94
Q

How could the Big Crunch happen?

A

The density of the universe (without dark matter) would have to be MORE than a certain amount.

Dark energy would be limited and the expansion of the universe would reverse.

95
Q

What is the Doppler effect? How is it linked to red and blue shift?

A

The effect that as an object moves away from us, the sound or light waves emitted by the object are stretched out, which makes them have a lower pitch and moves them towards the red end of the electromagnetic spectrum, where light has a longer wavelength (RL) - links to red-shift

And as an object moves towards us, the sound or light waves emitted by the object are squashed, which makes them have a higher pitch and moves them towards the blue end of the electromagnetic spectrum, where light has a shorter wavelength - links to blue-shift

THINK F1:

  • towards you = high pitch
  • away from you = low pitch

GCSE Physics (18 decks)

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