Everything Earth Flashcards
1
Q
What shape is the earth?
A
An olbate spheriod
2
Q
What is the mean diameter of the earth?
A
13000km
3
Q
What are the layers of the earth?
A
Inner Core
Outer Core
Mantle
Crust
4
Q
What is the composition of the Crust?
A
Oxygen, Aluminium, Silicon
1% of earths volume
Solid
5
Q
What is the composition of the Mantle?
A
Silicate rocks, Magnesium, Iron
84% of earths volume
Solid/Plastic
6
Q
What is the composition of the Outer Core?
A
Iron, Nickel
15% of earths volume (between both parts of the core)
Liquid
7
Q
What is the composition of the Inner Core?
A
Iron, Nickel
15% of earths volume (between both parts of the core)
Solid
8
Q
Is the Earth’s Diameter greater N↔S or W↔E ?
A
East↔West (by about 43km)
9
Q
What is Latitude, and what is its range?
A
Position from the Equator [90°S,90°N] 90°N is Nouth Pole 0° is Equator 90°S is South Pole
10
Q
What is Longitude, and what is its range?
A
Position from the Prime Meridian
[-180°,+180°]
-180° and +180° is the International Date Line
0° is Prime Meridian (Greenwich)
11
Q
What is the Tropic of Cancer?
A
23.5°N Line of Latitude
Latitude which has the sun at its zenith on the Summer Solstice (21st June)
12
Q
What is the Tropic of Capricorn?
A
23.5°S Line of Latitude
Latitude which has the sun at its zenith on the Winter Solstice (21st December)
13
Q
What is the Arctic Circle?
A
66.5°N Line of Latitude
Above which the sun will not rise or set for at least one day
Sun wont rise on Winter Solstice (21st December)
Sun wont set on Summer Solstice (21 June)
14
Q
What is the Antarctic Circle?
A
66.5°S Line of Latitude
Below which the sun will not rise or set for at least one day
Sun wont set on Winter Solstice (21st December)
Sun wont rise on Summer Solstice (21 June)
15
Q
What is the Composition of the Atmosphere?
A
78% Nitrogen 21% Oxygen 1% Argon 1% Water 0.4% Carbon Dioxide
16
Q
What are benifits of the Atmosphere?
A
Respiration
Absorbs UV, X-ray and γ-ray
Regulates/moderates temperature
Limited protection from small meteoroids
17
Q
What are drawbacks of the Atmosphere?
A
Refraction EM waves (rayleigh scattering)
Absorbtion (for looking at space)
18
Q
When do Solar Eclipses occur?
A
At New Moons
19
Q
What is the Penumbra?
A
Outer part of the shadow created by a celestial body
Partial Eclipse
20
Q
What is the Umbra?
A
Inner part of the shadow created by a celestial body
Total Eclipse
21
Q
When do Lunar Eclipses occur
A
At Full Moons
22
Q
What are the 4 Points of Contact?
A
First Contact (Moon and Sun first touch) Second Contact (Beginning of Totality) Third Contact (End of Totality) Forth Contact (Moon and Sun part)
23
Q
What is a Total Eclipse?
A
Complete covering of the Sun by the Moon.
≈160km across
Once or twice a year
24
Q
What is an Annular Eclipse?
A
Total Eclipse where the moon is further from the earth and, thus cannot completely cover the sun
(Moon further away due to orbital eccentricity)
25
What is a Lunar Eclipse?
When the shadow of the Earth obscures the moon
26
Why don't Lunar Eclipses occur monthly?
The eccliptic planes of the sun and moon don't allign much.
27
What is the length of time between Tides?
High→low is ≈6h
| High→high is ≈12h
28
How much earlier do tides occur each day?
≈50 minutes
| Due to the period of the Moon's orbit
29
When do Spring Tides occur?
When the Sun and Moon are alligned with the Earth
| Full or New Moon
30
When do Neap Tides occur?
When the Sun is 90° from the Moon
| First or Last Quater
31
What is Precession?
The moving of the axis of rotation
| A single precession on Earth lasts 26000 years
32
What is the Angular Diameter of the Sun?
≈ 0.5°
33
What is the Angular Diameter of the Moon?
≈ 0.5°
34
What is an Astronomical Unit?
The mean distance between the Earth and the Sun
| 150x10^8
35
How did Halley propose to measure the scale of the Solar System?
The difference in time of the transit of Venus, as it would appear different for different Latitudes on Earth. This could be used to calculate an angle, then a distance.
36
Which direction do the planets travel when viewed from the North Pole?
Anti-Clockwise (Prograde)
37
How does the Daily Motion of the Planets appear?
East→West (Prograde)
38
How does the Monthly Motion of the Planets appear?
West←East
39
Why can Superior Planets appear to have Retrograde Motion?
It is an illusion caused by Earth passing the Superior Planets in their orbit
40
What is an Inferior Planet?
A Planet closer to the Sun than Earth
41
What is a Superior Planet?
A Planet further from the Sun than Earth
42
What is Elongation?
The angle between a Planet and the sun when viewed from Earth
43
When are Superior Planets at greatest Elongation?
When on the opposite side of Earth to the Sun
| 180°
44
What is the greatest angle of Elongation of Venus?
47°
45
What is the greatest angle of Elongation of Mercury?
28°
46
What is the Superior Conjunction of a Planet?
When the Planet is the other side of the Sun from the Earth.
| Big in front of small
47
What is the Inferior Conjunction of a Superior Planet?
When the Planet is the same side of the Sun as the Earth
| Small in front of big
48
When is a Planet at Opposition?
When it is the opposite side of the Earth to the Sun
49
What has been found due to Occulation?
Evidence of no Lunar atmosphere
The rings of Uranus
The first Quasar
50
What is Occulation?
When a smaller body passes behind a larger one
51
Who theorised the Geocentric model?
Ptolemy theorised
52
What was used to explain the Retrograde motion of the Superior Planets in the Geocentric model?
Epicycles
53
Who suggested the Heliocentric model?
Nicholas Copernicus
54
What could Heliocentric do but geocentric couldn't ?
Easily explain the Retrograde Motion of Superior Planets
55
Who first measured the Circumference (thus calculating the diameter) of Earth?
Eratosthenes
56
Who first calulated the Diameter, Distance to the moon and Distance to the Sun?
Aristarchus
57
What did Tycho Brahe do?
He took a large number of accurate observations of the planets positions.
58
What did Johannes Kepler do?
Formulated the Laws of Planetary Motion
59
What did Galileo Galilei discover?
Phases of Venus
4 main moons of Jupiter (Callisto, Europa, Ganymede and Io)
Relief features of the Moon (Showed it wasn't flat)
Sunspots
Resolved the Milky Way into Stars
60
What did Isaac Newton do?
Formulated the Laws of Gravitation
| Thus proving the laws of planetary motion
61
What is the 1st Law of Planetary Motion?
Planets move in elliptical orbits with the Sun at one focus
| the closer the foci the more circular the orbit
62
What is the name of the Closest and Furthest points from the Sun in an orbit?
Closest: Perihelion
Furthest: Aphelion
63
What is the name of the Closest and Furthest points from the Earth in an orbit?
Closest: Perigee
Furthest: Apogee
64
What is the 2nd Law of Planetary Motion?
The Sun-Planet line sweeps out equal areas in equal times
65
What is the 3rd Law of Planetary Motion?
The orbital period of a planet squared is proportional to the mean distance from the Sun cubed
T²∝r³
66
What is the equation of the 3rd Law of Planetary Motion?
T² = 4π²r³/GM
67
Where is the Sun located on the Spring Equinox?
First Point of Aries
(0°, 0°)
0 hours, 0 degrees
68
Where is the Sun located on the Autumn Equinox?
First Point of Libra
(180°, 0°)
12 hours, 0 degrees
69
What is the Ecliptic?
The great circle which is the path of the Sun on the Celestial Sphere
It is 23.5° from the Celestail Equator
70
What is the Celestial Sphere?
An imaginary sphere surrounding the earth on which all celestail objects are placed
71
Where is the Sun located on the Winter Solstice?
(270°, -23.5°)
18 hours, -23.5 degrees
Over the Tropic of Capricorn
72
where is the Sun located on the Summer Solstice?
(90°, 23.5°)
6 hours, +23.5 degrees
Over the Tropic of Capricorn
73
What are Horizon Coordinates?
A celestial coordinate system based off of the observers location and time of viewing
74
How are Horizon Coordinates recorded?
Altitude:
The angle between the observers horizon and the
object.
Azimuth:
The bearing of the obect taken from true north
75
What is the Meridian?
The observers based line which run North-South through the Zenith
76
What is Diurnal Motion?
The apparent motion of an object due to the daily rotaion of Earth
77
What is Culmination?
When the object is at its greatest altitude
| often best time to observe
78
What is Local Sidereal Time?
The Sidereal time of your location
| Time since first point of aries crossed the meridian
79
What is Hour Angle?
The time since an object last culminated
| Measured in sidereal time
80
What links Hour Angle, Local Sidereal Time and Right Ascension?
Hour Angle = Local Sidereal Time - Right Ascension
81
When does a star Culminate?
When Right Ascension = Local Sidereal Time
| RA = LST
82
What does a negative Hour Angle indicate?
How long it is till the star culminates
83
What deos it mean for a star to be Circumpolar?
That the star will not set below the observers horizon
84
When is a star Circumpolar?
Declination > 90° - Observers Latitude
| Declination > Co-latitude
85
Why do Circumpolar stars cross the Meridian twice?
Once above the NCP
| Once Below the SCP
86
What Enviromental details should observations include?
```
Date
Time
Location (lat/long)
Weather (opacity of sky)
Seeing Conditions (stability of atmosphere (Defration))
Intsrumetation
```
87
Give three Naked-Eye Observing techniques?
Dark Adapted Eye: 20 mins in dark and light sensitive chemical is released in eye.
Relaxed Eye: Eye isn't strained
Averted Vision: Edge of vision is more sensitive to light
88
How would an Aircraft be Identified?
Navigation Lights
| Flashing Lights
89
How would a Satelite be Identified?
Slow Moving Light
Continuous Light
Disappears before horizon due to the Earths shadow
90
How would a Meteor be Identified?
Fast Moving Light
Streak of Light
Short Lasting
91
What is a Meteoriod?
Small irregular shaped lumps of debris in the Solar System
| Roughly up to 10m
92
What is a Meteor (Shooting Star)?
Streak of Light lasting a second
| Occur when Meteoriod hits atmosphere
93
What is a FireBall?
Meteor which is brighter than -3
| Also a Brilliant scientific term
94
What is a Meteorite?
A meteoroid which has survived the atmosphere and landed
95
What is the Difference between Sporadic Meteors and Meteor Showers?
Sporadic: Random
Shower: Regular
96
What is the Radiant Point of a Meteor Shower and how can it be found?
It is the point all the meteors appear to originate from (due to perspective).
It can be found by tracing back the paths of the meteors to a point where they all cross.
97
What is significant about the Radiant Point of a Meteor Shower?
It gives the shower its name
| eg. Radiant in Orion give the name Orionids
98
What is the Messier Catalogue and why was it created?
List of 110 fuzzy celestial object.
It was created as a list by Charles Messier who was looking for comets but made a list of things which aren't comets
Shown by having M before a number (eg No 1 in catalogue is M1)
99
What is a Nebula?
Plural: Nebulae
Diffuse fuzzy clouds, irregular in shape
appear large with low surface brightness
eg. M1 Crab Nebula
100
What is an Open Cluster?
Region of newly formed, hot, young stars in an irregular shape
They are within the Milky Way
eg. M45 Pleiades (Seven Sisters)
101
What is a Globular Cluster
Region of old, compact stars
They are in a halo around the Milky Way
eg. M13
102
How many Constellations are there?
88 International Astronomical Union recognised ones
103
How is the brightness of stars within Constellations listed?
α is brightest
β is second brightest
then γ, δ, ε ...
(Not all are in the correct order due to wavelengths which human cannot see as well)
104
What is an Asterism?
```
Smaller part of a constellation
eg. Plough/Saucepan
Or
Stars forming a pattern between serveral constellation
eg. Square of Pegasus
```
105
What is a Pointer?
Two or more stars which can be used to form a line that points to another object of interest
106
What is Synodic Time?
Measurement of time using the motion of the Sun
≈ 24 hours
Solar Time
(Clock/Normal time)
107
What is Sidereal Time?
Measurment of tiem using the motion of the stars
| 24 Sidereal hours is 23 hours 56 minutes 4 seconds in Synodic
108
How long is a Sidereal Day?
23h 56mins 4 sec
| True rotational period of the Earth
109
How can a Sidereal Day be calculated?
The angle subtended by a star trail on a long exposure circumpolar photo needs to be measured, as well as its exposure time.
Sidereal Day/Exposure Time = 360°/Angle of star trail
110
What is and how long is a Sidereal Month?
Time taken for the the Moon to revolve around the Earth (and spin on its axis as tidally locked)
27.3 days
111
What is and how long is a Synodic Month?
Time taken for the Moon to complete a Lunar Phase
| 29.5 days
112
What are the 8 Phases of the Moon and when do they occur?
```
New Moon 12:00 (Spring Tides and Solar Eclipses)
Waxing Cresent
First Quater 18:00 (Neap Tides)
Waxing Gibbous
Full Moon 00:00 (Spring Tides)
Waning Gibbous
Last Quater 06:00 (Neap Tides)
Waxing Cresent
```
113
What is AST?
Apparent Solar Time
Synodic Time of your position
(Sundial Time)
114
What is a MST Day?
Exactly 24 hours
| Mean time taken for the Sun to cross the Observers meridian
115
What is MST?
The regulated time which is used
| eg. clocks and time zones
116
Why can the MST be different to AST?
Earths tilt to the ecliptic
| Orbital eccentricity
117
What is ET?
Equation of Time
| The difference between AST and MST
118
What equation links ET, AST and MST?
MST = AST - ET
| Clock time = Sundial time - Difference
