Topic 1:earth,moon and sun Flashcards
1
Q
What are key features of the earth
A
- it’s atmosphere is mainly oxygen (21%)and nitrogen (78%) it also contains argon(1%) and carbon dioxide (0.04%)
- liquid water covering about 70% of the surface
- life in all its diverse forms
2
Q
What is the diameter of the earth
A
13,000km
3
Q
What shape is the earth
A
Oblate spheroid
4
Q
What evidence suggests that the earth is spherical
A
- ships disappear over the horizon
- satellites orbit the earth-impossible with a flat earth
- the curvature of the earths shadow during a partial lunar eclipse
- images of earth from space
5
Q
What is latitude
A
The angle between a point on the earth’s surface, the centre of the earth and a point on the equator
6
Q
How do the lines of longitude run on a globe
A
They converge towards the poles
7
Q
How much is the Earth’s polar axis tilted by
A
66.5 degrees to the ecliptic
8
Q
What is the ecliptic
A
The plane on which the Earth orbits the sun
9
Q
What is the longitude
A
The angular displacement east or west of the observers meridian from the prime meridian
10
Q
What is the meridian
A
A circle of constant longitude passing through a given place on the earths surface and the terrestrial poles
11
Q
What is the zenith
A
The point in the sky or celestial sphere directly above an observer
12
Q
What is an observers horizon
A
The imaginary plane that meets the observer at a tangent to the Earth’s surface
13
Q
What are the main sources of terrestrial light pollution
A
- commercial and sports floodlights
- urban street lamps and motorway lights
- lights above car parks and shopping centres
14
Q
What is the height of the atmosphere
A
100km
15
Q
What benefits does our atmosphere provide is with
A
- it absorbs harmful solar ultraviolet radiation
- it absorbs harmful energetic x-rays and gamma-rays from space and prevents them from reaching the ground
- it provides us with oxygen to breathe
16
Q
What are the drawbacks of our atmosphere
A
- the refraction of light as it passes through our turbulent atmosphere, causing stars to ‘twinkle’ and therefore restricts the resolution of an image
- the selective scattering of shorter wavelengths of sunlight by gas molecules in the atmosphere, making the sky appear blue and so astronomers cannot observe during the day
17
Q
What effects does the atmosphere have on radiation
A
- the longest waves are reflected back into space by electrons in the ionosphere
- some shorter wavelength microwaves are absorbed by water vapour and oxygen
- ultra-violet radiation is absorbed by ozone and , at shorter wavelengths oxygen
18
Q
What is a refractor telescope
A
A telescope in which a glass convex lens collects the light and brings it in to a focus
19
Q
What is a reflector telescope
A
A telescope in which a curved mirror collects light
20
Q
What is the lens or mirror in a telescope called
A
The objective
21
Q
What are the advantages of large telescopes
A
- the collection of more light
* higher resolution in better proportional diameter
22
Q
What do ideal observing sites consider
A
- atmospheric properties such as cloud cover, air turbulence, sky brightness, water vapour content
- geographic location- access, utilities, likelihood of earthquakes and ground stability
23
Q
What are the benefits of using telescopes in space
A
- no atmosphere to reduce resolution
- no light pollution
- no adverse weather problems
24
Q
What are drawbacks to using space telescopes
A
- More expensive to build and launch into orbit
- reduced lifetime ;
* difficult/impossible maintenance/repairs/. upgrades
25
What are the van Allen belts
Two doughnut-shaped rings of spiralling high-energy particles held in place by the earth's magnetic field.
26
What are the inner van Allen belts made of and how were they formed
The compact inner belt consists mainly of high-energy protons formed by collisions between cosmic rays and atoms in the atmosphere
27
What are the outer van Allen belts made of
Consists mainly of electrons and other charged particles emitted by the sun as a result of increased solar activity
28
What is the diameter of the moon
About 3,500km
29
What is the mean distance that the moon orbits the Earth at
380,000 km
30
What is the moons rotational and orbital period
27.3 days
31
What are rilles on the moon
Narrow channel-like depressions in the lunar seas that can either be straight,smoothly-curved or sinuous . They are caused by lava flows
32
What are wrinkle ridges
They are caused by the buckling of the lunar surface as a result of compressive forces within the cooling, contracting lava, forming ridges up to hundreds of kilometres long
33
Name 3 objectives of NASA's Apollo space programme
* the collection of lunar soil and rock for analysis
* the deployment of scientific experiments on the lunar surface
* land a man on the Moon and return him safely to Earth
34
What were some of the instruments in each ALSEP (apollo lunar surface experiment package) employed to measure, analyse and monitor
* the structure of the moons interior
* lunar dust
* the intensity and direction of the solar wind
35
What hypothesis is believed to be true for the formation of the Moon
The Giant Impact Hypothesis- in which the relatively young Earth was struck by a mars-sized object known as Theia . Theia and a large portion of the earths outer layers melted and merged, and at the same time a huge amount of debris was thrown into the Earth-orbit. This material coalesced and cool d to formed what is now the moon
36
What is the diameter of the sun
1.4 million km
37
How far away is the sun from Earth
150 million km
38
What is the temperature of the photosphere
5800 k
39
What is the 'visible' surface of the sun
Photosphere
40
What gasses make up the sun
75% hydrogen and 25% helium
41
What makes up the suns atmosphere
The chromosphere and the corona
42
How thick is the suns atmosphere
2,000km
43
What is the temperature of the corona
2 million k
44
Why does the sun shine
Because it is able to turn gravity into light- happens because hydrogen gas in the core gets squeezed together so tightly that 4 hydrogen nuclei combine to form one helium atom, this is called thermonuclear fusion
45
What is the safest way to view the sun
Use and indirect projection method in which a pinhole camera, pair of binoculars or a telescope focuses an enlarged image of the sun onto a screen, reducing the brightness to a safe level
46
What are sunspots
Small dark patches on the photosphere and they are cooler areas of the photosphere
47
What is an umbra
A central darker region, about 2,000 k cooler than the photosphere
48
What is a penumbra
A lighter surrounding area, with a temperature about 200 k cooler than the photosphere
49
What is the suns rotational period
25 days at the equator and 36 days at its poles
50
What is solar wind
A steady stream of charged particles (mainly protons and electrons, but with traces of ions of helium and other elements)
51
Where is solar wind found
Flowing outwards in all directions from the suns corona at speeds of typically 400km/s
52
What are coronal holes
Cooler region of the corona close to the suns magnetic poles
53
What happens when a telescope is fitted with a H-alpha filter
The filter allows a narrow range of wavelengths either side of 656nm to pass through and block the remaining light. The increased contrast allows solar features to be observed clearly
54
What are prominences
Huge clouds of cooler gas in the sun's atmosphere
55
What are filaments
Huge clouds of cooler gas in the sun's atmosphere that appear as dark silhouettes against the brighter photosphere
56
What are solar flares
Sudden releases of energy
57
What happens when an x-ray filter is used
Exceptionally hot regions of the sun emit x-rays and so an x-ray filter allows you to see them
58
How long is the lunar cycle
29.5 days
59
Why is the moon visible
Because it reflects sunlight
60
What is a solar eclipse
When the moon is on the ecliptic and it moves directly in front of it and so blocking it out
61
What phase does the moon have to be in for a solar eclipse to happen
New moon
62
Why don't solar eclipses happen every new moon
Because the plane of the moon's orbit around the earth is tilted slightly to the plane of the earth's orbit around the sun.this means that at most new moon's the moon is either 'above' or 'below' the sun in the sky
63
What is a lunar eclipse
When the moon is on the ecliptic and it moves directly behind the earth so that the light from the sun is blocked out
64
What phase doe the moon have to be for a lunar eclipse to happen
Full moon
65
Why does the moon go red/orange in a lunar eclipse
The light from the sun passes through the atmosphere around the edge of the the Earth and most blue light is scattered to leave mainly red light.this red light is refracted by the Earth's atmosphere and illuminates the moon
66
How long is a sidereal day
23 hrs 56 min
67
How long is a solar day
24hrs
68
Why doesn't the sun move over the sky in a uniform matter every day
* the earth orbits the sun in an elliptical orbit
* the earth's polar axis is tilted to the plane of its orbit,causing the sun to b 'higher' no the sky in summer compared to winter
69
What is the equation of time
EOT=apparent solar time-mean solar time (GMT)
70
What are Aurorae caused by
Electrons from solar wind, that have been accelerated to high speeds in the Earth's magnetic field , exciting atoms and molecules of oxygen and nitrogen in the upper atmosphere. As the atoms de-excite, they emit light at certain wavelengths that are characteristic of the element concerned
71
What is the Tropic of Cancer
The circle marking the latitude 23.5o north- where the sun is directly overhead at noon on June 21
72
What is the Tropic of Capricorn
The circle marking 23.5o south- where the sun is directly overhead on December 21
73
How is the far side different to the near side of the moon
Less Maria and more crators
74
What month do shadow sticks give the shortest shadows at noon in the U.K.
June
75
What does a sunrise determine
The apparent solar time
76
What was the name of the first successful manned exploration of the moon
Apollo 11 in 1969
77
What did Eratosthenes observe
He read an account that at noon on the date of the summer solstice in Syene on the Tropic of Cancer, the sun lay directly over a well. Furthermore, vertical sticks and columns of temples did not cast any shadows at that precise time in Syene
78
What was Eratosthenes method
Measurements of the suns position at noon in alexandria on the summer solstice showed that it was just over 7° from the zenith which is equivalent to almost exactly 1/50th of a circle
He learnt that Syene was the
equivalent of 790 km further south the Alexandria and so he used geometry to deduce that the circumference of the earth was 50 times this value i.e. 39,500km
79
When if the summer solstice
21st June
