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Astronomy GCSE Edexcel > Topic One: Earth, Moon and Sun > Flashcards

Topic One: Earth, Moon and Sun Flashcards

(100 cards)

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1
Q

What are three features that distinguish the Earth from other planets?

A

Atmosphere
Water
Life

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2
Q

Describe the makeup of Earth’s atmosphere:

A

Nitrogen 78%
Oxygen 21%
Argon 1%
Carbon Dioxide 0.04%

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3
Q

What is the diameter of the Earth?

A

roughly 13,000km

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4
Q

What is the shape of the Earth?

A

Oblate Spheroid

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5
Q

Give six pieces of evidence to suggest the Earth is not flat:

A
  1. Ships disappear below the horizon
  2. Satellites orbit the Earth
  3. The curvature of the Earth’s shadow during a partial lunar eclipse
  4. Aircraft fly in arcs rather than in straight lines
  5. Images of Earth from space
  6. Eratosthenes (because shadows of an object at the same time of day should be the same if earth was flat)
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6
Q

Define Latitude

A

The angle between a point on the Earth’s surface, the centre of the Earth and the equator. Expressed as an angle in North of South of the equator

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7
Q

Describe the Earth’s polar axis:

A

Titled by 66.5 degrees to the plane of the ecliptic

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8
Q

What is the Ecliptic?

A

It is the plane on which the Earth orbits the sun

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9
Q

Define equinox

A

When the sun resides directly above the equator

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10
Q

When is the spring equinox?

A

21st March

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11
Q

When is the autumnal equinox?

A

22nd/23rd September

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12
Q

What is a Solstice?

A

When the sun resides directly over the Tropic of Cancer (21st June) or the Tropic of Capricorn (21st December)

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13
Q

What is a Meridian?

A

An imaginary North to South line running directly through the observers zenith

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14
Q

Define Longitude

A

The angular displacement east or west of the Prime Meridian

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15
Q

Define Zenith

A

A point directly above the observer

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16
Q

Define Horizon

A

The imaginary line along which the sky meets the sea/land

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17
Q

What are the main causes of skyglow?

A

Floodlights
Streetlights
Car parks + shopping centres

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18
Q

What did Eratosthenes do?

A

Measured Earth’s circumfrence

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19
Q

When did Eratosthenes measure the Earth’s circumference?

A

3rd Century BC

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20
Q

How did Eratosthenes measure the Earth’s circumference?

A

He read that at noon on the Summer Solstice, no shadows were casted in Syrene
At the same time in Alexandria, the suns position was 7 degrees (one 50th of a circle) from the Zenith
He knew that the distance from Syrene to Alexandria was 790km and used simple geometry to work out the circumfrence of the Earth was 50x this

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21
Q

What are the benefits of Earth’s atmosphere?

A

Absorbs harmful UV radiation that causes skin cancer

Absorbs harmful gamma and x-rays

Regulates temperature, allowing liquid water

Provides us with oxygen

Protects us from PHOs

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22
Q

What are the drawbacks of the atmosphere for astronomers?

A

Not all the wavelengths reach Earth so many telescopes have to be placed on satellites

Refraction spikes restrict resolution

Light scattering makes the sky appear blue, meaning astronomers can only observe during the night

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23
Q

What are the “windows” that allow EMR to hit the ground?

A

Optical Window

Radio Window

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24
Q

Describe the effects of the atmosphere on Electromagnetic Radiation:

A

Long wavelengths reflected back into space by electrons in the ionosphere

Short wavelengths absorbed

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25
What is Infra-Red radiation absorbed by in the atmosphere?
Carbon Dioxide, water vapour and methane
26
What is UV radiation absorbed by?
The Ozone
27
What are X-rays and Gamma Rays absorbed by?
Oxygen and Nitrogen
28
What are the main functions of a telescope?
They collect light | They produce a focused image
29
What are the two fundamental types of a telescope?
Reflector - curved mirror collects light and focuses it Refractor - convex lens collect light and focuses
30
What is the objective?
The lens or the mirror of a telescope
31
Name two considerations when choosing an observing site:
Atmosphere (Cloud, Air turbulence, skyglow, water vapour) Geographic location (Access, utilities, ground stability)
32
What are the advantages of large telescopes over small telescopes?
Collection of more light Higher resolution (less diffraction) Observing times can be shorter
33
What are the advantages of using telescopes in orbit?
No atmosphere - greater resolution, other wavelengths No light pollution
34
What are the disadvantages of using telescopes in orbit?
Difficult to maintain/repair/upgrade - shorter lifetime, radiation damage, solar wind Expensive
35
What is the successor to the Hubble Space Telescope?
The James Web Space Telescope
36
Why do Space telescopes have to be cooled to near absolute 0?
So they won't generate their own Infra-Red which will affect the results
37
What is the size of the objective on the JWST?
6.5m
38
When will the JWST launch?
2016
39
How will the JWST reduce the amount of coolant needed?
Open design so it doesn't trap hear Unusual orbit to use the Earth to shield from the Sun Large sun shield
40
Who discovered the Van Allen belts?
James A. Van Allen
41
Describe the Van Allen Belts:
Inner: 0.1-1.5 earth radii High energy protons Danger to astronauts and satellites Outer: 3-10 earth radii high energy electrons wider belt with 'horns' that dip towards the Earth's magnetic poles
42
What is the diameter of the Moon?
3500km
43
What is the average distance to the moon?
380,000km
44
What is the strength of Moon's Gravity?
1/6 G
45
Why do we only see one side of the moon?
Because the Moon's orbital period is equal to it's rotational period
46
What is the Moon's rotational period?
27.3 days
47
What is the Moon's orbital period?
27.3 days
48
What is the difference between the Moon's orbital and rotational period?
Trick question, they are the same. I tried to be funny, I'm not funny, revision has got me this bored ugh. I need friends.
49
What is the Lunar Cycle?
It is the time taken for the Moon to go through a cycle of phases in the sky when observed from Earth A lunar month is 29.5 days
50
Why is the Lunar Month 2.2 days longer than the Moon's orbital period?
An extra 2.2 days is needed to bring the Moon, the Sun and Earth back into alignment.
51
How and when did we first see the far side of the moon?
Russian Luna 3 October 1959 Dual lens camera
52
Who were the first humans to see the far side of the moon directly?
Apollo 8 astronauts in December 1968
53
Describe the lunar landscape (lunar seas):
Lunar seas: - Maria - Iron rich basaltic rock - Dark grey - Smooth
54
Describe the lunar landscape (Highlands):
Highlands: - Terrae - Anorthosite - Course grained igneous rock - Lighter grey - Heavily cratered
55
Describe the lunar landscape (Notable Features):
Notable Features: - Sea of Crises - Apennine Mountains - Sea of Tranquillity - Tycho Crater - Kepler Crater - Coppernicus crater - Ocean of Storms
56
Describe the lunar landscape (Rilles):
Rilles: - Narrow channel like depressions - Caused by lava flows
57
Describe the lunar landscape (Wrinkle ridges):
Wrinkle ridges: - Ridges up to 100s of km long - Caused by compressive forces within cooling lava
58
Why do we think the highland regions are older than the Lunar seas?
Smaller number of craters in the Lunar seas
59
What were the objectives of NASA's Apollo Programme?
To put men on the moon To collect lunar soil and rock for analysis To perform scientific experiments To beat the Russians
60
What went wrong with Apollo 1?
Launch Pad fire: - welded door shut - 3 astronauts unable to escape
61
Describe the Apollo 11 mission:
1969 Aldrin, Armstrong and Collins US Flag planted
62
How many humans have walked on the moon?
12
63
Describe the Condensation/Co-Formation hypothesis for the formation of the moon:
Earth and Moon formed at the same time and place This hypothesis is unlikely because the moon is less dense and has no iron core like Earth
64
Describe the Capture hypothesis for the formation of the moon:
The moon formed a great distance away from the Earth and was captured by Earth's gravity during close encounter
65
Describe the Fission hypothesis for the formation of the moon:
A rapidly spinning young Earth threw off a blob which formed the moon
66
Describe the Giant Impact Hypothesis for the formation of the moon:
Mars sized object hit Earth causing a large blob of Earth's outer layers melted and merged Large amounts of Debris thrown into Earth's orbit
67
Give 3 pieces of evidence to support the Giant Impact Hypothesis:
Oxygen Isotopes are the same on the moon and on the Earth Lack of water and volatile compounds -vaporised during the Moon's formation Kreep (potassium rare earth elements phosphorus) rocks found on the moon
68
What is the diameter of the Sun?
1. 4 million km | - 100 times the diameter of the Earth (13,000km)
69
What is the average distance from the Earth to the Sun?
150 million km
70
What is the composition of the Sun?
Hydrogen 75% Helium 25% Traces of other elements
71
Describe the Sun's surfaces:
Photosphere: - Visible surface - 5800k
72
Describe the Sun's atmosphere:
Thin Chromosphere: - 2000km thick - not visible unless during an eclipse Extensive Corona (Crown): - Also visible during an eclipse - Ionised gas 2 million kelvin - Hot enough to emit X-rays
73
Describe two methods we can use to observe the sun:
Project an image of the sun onto paper Use a special H-Alpha filter on a telescope
74
What is a sunspot?
Cooler regions on the surface (photosphere) of the Sun | -Correspond to strong local magnetic fields
75
Describe the structure of a sunspot:
Umbra : - 2000K cooler than the rest of the sun (3800K) Penumbra: -200K cooler than the photosphere (5600K)
76
Describe the rotation of the Sun:
The Sun doesn't rotate as a solid body - the equator takes 25 days to rotate - the poles take 36 days to rotate
77
What is the solar cycle?
The relative number of sunspots follows a regular 11 year pattern called the Solar Cycle
78
What is a butterfly diagram?
A graph of latitude of the spot on the sun's surface - at the beginning there are few sunspots at 35 to 40 degrees north and south - as the solar cycle progresses, there are more spots but their positions drift towards the equator
79
What is the solar wind?
A steady stream of charged particles from the corona - mostly electrons and protons - some helium ions
80
Describe the two types of solar wind:
Slow (400km/s) Fast (850km/s) - Fast originates at the poles since the magnetic field lines are open so particles can easily escape
81
What is H-Alpha light?
EMR emitted by ionised Hydrogen Gas | -656nm wavelength
82
What features of the sun can you observe using an H-Alpha filter?
Sunspots, Solar flares, Chromosphere
83
Why do the Sun and Moon appear to be the same size in the sky?
Because the Sun is 400x further away but also 400x larger in diameter
84
Why do we not have a total solar eclipse every month?
The ecliptic and the plain of the Moon's orbit around Earth are different
85
Describe a total solar eclipse:
Occurs at new moon Moon passes directly in front of the Sun Light from the Sun's photosphere obscured if observer is in the umbra
86
Describe a partial solar eclipse:
Moon only partly obscures light from the sun
87
What is a lunar eclipse?
Occurs at full moon, when the Earth passes between Sun and Moon, Moon given reddish glow
88
What type of eclipse is most common and why?
A lunar eclipse because it is visible from most of the Earth's night side
89
Why does the Moon appear red during a solar eclipse?
Because "blues bend best" | -light from the sun is refracted by the Earth's atmosphere
90
In which direction does the Earth spin?
From East to west
91
What is a sidereal day?
The actual time it takes for Earth to spin 360 degrees on its axis It is 23h 56min and 4.1 seconds
92
What is a Solar Day?
The time taken for succesive crossing of the Sun across the Observer's Meridian - an extra 4 minutes to allow the sun to return to the same position in the sky exactly 24h
93
What is the difference between AST and MST?
AST is the measure of Solar Day MST is the average Solar Day
94
Why does the Sun not move uniformly in the sky everyday?
The Earth orbits the sun in an elliptical orbit The Earth's polar axis is tilted to the plain of the ecliptic - Sun higher in the sky in Summer than in Winter
95
Name the Aurorae?
Aurora Borealis (Northern Lights) Aurora Australis (Southern Lights)
96
What casues the Aurorae?
Solar Wind
97
What is the speed of light in a vacuum?
3x10^8 m/s
98
What is one light year?
9.46x10^15 m
99
What is the formula for EoT?
EoT = AST - MST
100
What does GMT stand for?
Greenwich Mean Time (I always thought this standed for 'Good Morning Time', I don't know why, but I know always remember it through this, lol)

Astronomy GCSE Edexcel (6 decks)

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