Astronomy (paper1) Flashcards
(119 cards)
1
Q
What’s the geocentric model
A
Where everything orbits around the earth
2
Q
Who’s idea was the geocentric model
A
Ptolemy
3
Q
What’s the heliocentric model
A
Where everything revolves around the sun
4
Q
Why is it called heliocentric
A
Helio means helium which is made on the sun, and centric means at the centre
5
Q
Who’s idea was the heliocentric model
A
Polish astronomer Copernicus
6
Q
When was the telescope invented
A
End of the 16th century
7
Q
What did the telescope allow scientists to do
A
See objects in space in much greater detail and to find new objects
8
Q
What did Galileo discover
A
Jupiters 4 moons
9
Q
What did Galileo show by plotting the movements of jupiters moons
A
He showed that not everything orbited earth
10
Q
What’s the definition of a star
A
A huge ball of gas that radiates energy
11
Q
What’s the definition of a planet
A
A celestial body moving in an orbit around a star
12
Q
What’s the definition of a galaxy
A
Billions of stars together-ours is called the Milky Way
13
Q
What’s the definition of the solar system
A
The sun, planets, moon, asteroids and comets make up this
14
Q
What planets were discovered after telescopes improved
A
Uranus, Neptune and dwarf plant Pluto.
15
Q
Where are asteroids most commonly found
A
Between the orbits of mars and Jupiter
16
Q
What are comets mostly made up of
A
Ice
17
Q
How many planets and dwarf planets are in our solar system
A
8 planets and 5 dwarf planets
18
Q
What shape are the planets’ orbits
A
Elliptical (squashed circle)
19
Q
What is another name for a moon
A
A natural satellite
20
Q
What did the invention of photographs allow astronomers to do
A
Make more detailed observations and measurements than drawing
21
Q
How have computers helped astronomy
A
They increase the speed and detail with which information from satellites can be analysed
22
Q
What are computers used for in astronomy
A
Analysing
23
Q
What’s an advantage of telescopes in orbit
A
They have much clearer images than ground-based telescopes
24
Q
How come orbiting telescopes give clearer images?
A
Clouds and dust in the air don’t interfere with the picture
25
What's another way that we investigate our solar system
By using space probes
26
What does the Spitzer Space telescope detect
Infrared radiation from objects in space
27
When was the first soft landing on a comet
2014
28
What is the strength of gravity like of comets
Thousands of times weaker than the earths gravity
29
What was the lander called that landed on the comet
The Philae
30
How was the Philae lander designed to keep it on the surface of the comet
It's landing legs were fitted with screws, it had harpoons and a small thruster
31
What happened to the Philae lander
When it tried to land, it bounced 1 km away from the surface before eventually landing
32
Define weight
Your weight is the force of gravity acting on you
33
What does your weight depend on
Your mass and the gravitational field strength of the earth
34
What is gravitational field strength measured in
N/kg
35
What ''tis earths gravitational field strength
9.81 n/kg
36
What does the gravitational field strength on the surface of a body depend on
The mass of the body, and the distance from the centre to its surface (its radius)
37
The greater the mass and the smaller it's radius the what?
The greater it's surface gravity
38
What are the orbits of comets like
They are highly elliptical
39
What are artificial satellites used for
Communications and to observe the earth and space
40
What does the type of orbit for an artificial satellite depend on
It depends on what it's used for
41
What are the four types of orbit for an artificial satellite
Polar orbit, highly elliptical orbit, circular geostationary orbits, and low earth orbits
42
What is circular geostationary orbits used for
They are used for broadcasting as they stay in the same place
43
How fast do satellites in circular geostationary orbits go
3070 m/s
44
Which type of orbit needs the least amount of energy to launch
Low earth orbit
45
How fast do satellites in low earth orbit go
7500m/s
46
What are highly elliptical orbits used for
Communication in parts of the earth near the poles
47
What happens to a satellite in polar orbit
It eventually passes over all parts of the earth
48
Describe what happens to a satellite in a circular orbit
It's speed stays the same but it's direction is constantly changing
49
What is velocity
A vector quantity
50
What does an orbiting body have
A constantly changing velocity
51
What happens to a moving object when a force acts on it
It will change speed or direction
52
Why do satellites change direction and not speed
Because the gravitational force between the earth and the satellite is at right angles to the direction of movements so force changes its direction and not the speed
53
When is the gravitational force on a satellite greater?
When it's in low orbit
54
What does the satellite in low orbit have to do to stay in the correct place
It must go faster than in higher orbit
55
What would happen to a satellite if it slowed down
It would fall towards the earth
56
What happens when a satellite is falling towards the earth
It gains speed, and when it's going fast enough it will stay in that new, lower orbit
57
What happens if the satellite goes low enough to encounter the atmosphere
Contact with the air would slow it down and it would eventually fall to the earth
58
What does the sun do for our planet
Provides enough energy to keep Earth at a liveable temperature
59
What is the next stage for the sun
To turn into a red giant
60
What will happen when the sun turns into a red giant
It will expand and swallow earth
61
Why isn't the sun turning a red giant a problem for humans
Because the heat from the sun will kill all life before it happens
62
Why won't the sun ever become a red supergiant
Because it's not heat enough
63
What is a nebula
A collection of dust and gases
64
What gas mainly exists in a nebula
Hydrogen
65
How does the sun provide thermal energy
Nuclear fusion(between helium and hydrogen)
66
How are the particles in a nebula pulled together
By their own gravitational force
67
What happens when a nebula cloud condenses
It becomes denser and the hydrogen becomes hotter as it spirals inwards
68
What happens when more mass is attracted to a nebula
The gravitational pull gets stronger and heats the material up even more
69
What is a made after a nebula has gone through all the phases
A protostar
70
What happens when the pressures and temperatures in the protostar become high enough
It forces hydrogen nuclei to fuse and make helium
71
What type of radiation do fusion reactions cause
A lot of Electromagnetic radiation
72
What balances out the outward pressure from the hot gases due to compression?
Gravity balances it out
73
What stage is our sun in
THe main sequence stage
74
What stage comes after hydrogen fusion of the protostar
The main sequence stage
75
How long do stars like our sun stay stable for
10 billion years
76
What happens to a star once it's reached the end of the main sequence
They have fused most of their hydrogen and helium, and the core isn't hot enough to withstand the gravity and it collapses. The outer layers expand to form a red giant, which is a lot bigger
77
What fusion reactions happen inside a red giant
Combining helium nuclei to form heavier elements
78
How long does the star stay a red giant for
A billion years
79
What happens after a star has been a red giant for a billion years
It throws off a shell of gas and the rest of the planet collapses to form a white dwarf which is much smaller
80
What happens inside a white dwarf
No union reactions take place, so it cools down for about a billion years and then forms a black dwarf
81
What are some characteristics of stars that are considerably larger than the sun(in mass)
They are hotter and brighter
82
What happens to massive main sequence stars
They fuse hydrogen and helium faster so they become a red super giant
83
What happens at the end of a red supergiant period
It rapidly collapses then explodes into a supernova
84
What happens to the outer layers of a red supergiant after it explodes
They are cast off and expand outwards
85
What happens to a supernova if it's mass is 4 times that of the suns
Gravity pulls the remains together and makes a black hole
86
Why can't light escape out of a black hole
Because the gravitational pull is so strong
87
What happens if the remains of a red supergiant aren't big enough to for a black hole
Gravity pulls them together to form a very dense, small star called a neutron stars
88
What does measuring red shift show us
That objects that are further away are moving faster than objects that are close to us
89
What does red shift explain
That the universe is expanding
90
When was the Big Bang theory first explained
In the 1920s
91
Explain the Big Bang theory
It's the theory that the whole universe and all the matter in it started off as a tiny point of concentrated energy 13.5 billion years ago
92
What is the other theory that opposes the Big Bang
The steady state theory
93
What is the steady state theory
The theory where new matter fills up the space when the universe expands
94
What does the Big Bang theory say about radiation
That huge amounts of radiation was released
95
How was CMBR found
By accident while two astronomers were building a radio telescope
96
What has happened to the wavelength of CMBR seen as though the earth is expanding
The wavelengths have increased, so it can now only be destructed as microwave radiation
97
What does CMBR stand for
Cosmic microwave background radiation
98
What do both the Big Bang theory and the steady strategy theory say
That the universe is expanding
99
Does redshift support both theories
Yes
100
What theory does CMBR support
Big Bang, as steady state does not say this
101
Which theory is more widely accepted by astronomers
The Big Bang
102
What does the pitch of a sound depend on
Frequency of a sound wave
103
What's the Doppler effect
The effect that when a sound gets further away from you, the pitch gets lower
104
What makes the wavelengths of a sound wave get longer
When the sound waves are behind a moving sound source, so they become stretched
105
What does making the wavelengths longer effect
It lowers their frequency which in turn lowers the pitch
106
What happens if a sound wave is in front of a moving sound source
The opposite
107
What is the condition with the Doppler effect
It only happens if you are moving at a different speed or velocity to the moving sound source
108
What other type of wave can have a Doppler effect
A light wave
109
What does the visible spectrum of light from stars contain
Patterns of dark lines
110
What is happening if the visible spectrum of light from stars is getting red-shifted
The star is moving away from us
111
What does red-shifted mean
That the rays of light are being moved towards the red end of the spectrum
112
The further the lines of light are shifted, the what?
The faster the star is moving relative to us
113
What is red shift a measure of
How far along the spectrum the lines have moved
114
What happens to visible spectrum of light from a star is the star is moving towards us
The wavelength and the frequency of the light waves become shorter, and move towards the blue side of the spectrum
115
Who investigated Redshift
Edward Hubble
116
In more detail, what did Edward Hubble investigate
How far the pattern of lines was shifted for around 50 galaxies in comparison to the sun
117
What did Edward conclude
That all the galaxies were moving away from us as they were all red-shifted
118
What did Edward also find out
That the further the galaxy was away from us, the greater the red-shift and so the faster it was moving away
119
How do we interpret red-shift in terms of our universe
That the universe is expanding
