Everything Earth Flashcards
What shape is the earth?
An olbate spheriod
What is the mean diameter of the earth?
13000km
What are the layers of the earth?
Inner Core
Outer Core
Mantle
Crust
What is the composition of the Crust?
Oxygen, Aluminium, Silicon
1% of earths volume
Solid
What is the composition of the Mantle?
Silicate rocks, Magnesium, Iron
84% of earths volume
Solid/Plastic
What is the composition of the Outer Core?
Iron, Nickel
15% of earths volume (between both parts of the core)
Liquid
What is the composition of the Inner Core?
Iron, Nickel
15% of earths volume (between both parts of the core)
Solid
Is the Earth’s Diameter greater N↔S or W↔E ?
East↔West (by about 43km)
What is Latitude, and what is its range?
Position from the Equator [90°S,90°N] 90°N is Nouth Pole 0° is Equator 90°S is South Pole
What is Longitude, and what is its range?
Position from the Prime Meridian
[-180°,+180°]
-180° and +180° is the International Date Line
0° is Prime Meridian (Greenwich)
What is the Tropic of Cancer?
23.5°N Line of Latitude
Latitude which has the sun at its zenith on the Summer Solstice (21st June)
What is the Tropic of Capricorn?
23.5°S Line of Latitude
Latitude which has the sun at its zenith on the Winter Solstice (21st December)
What is the Arctic Circle?
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)
What is the Antarctic Circle?
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)
What is the Composition of the Atmosphere?
78% Nitrogen 21% Oxygen 1% Argon 1% Water 0.4% Carbon Dioxide
What are benifits of the Atmosphere?
Respiration
Absorbs UV, X-ray and γ-ray
Regulates/moderates temperature
Limited protection from small meteoroids
What are drawbacks of the Atmosphere?
Refraction EM waves (rayleigh scattering)
Absorbtion (for looking at space)
When do Solar Eclipses occur?
At New Moons
What is the Penumbra?
Outer part of the shadow created by a celestial body
Partial Eclipse
What is the Umbra?
Inner part of the shadow created by a celestial body
Total Eclipse
When do Lunar Eclipses occur
At Full Moons
What are the 4 Points of Contact?
First Contact (Moon and Sun first touch) Second Contact (Beginning of Totality) Third Contact (End of Totality) Forth Contact (Moon and Sun part)
What is a Total Eclipse?
Complete covering of the Sun by the Moon.
≈160km across
Once or twice a year
What is an Annular Eclipse?
Total Eclipse where the moon is further from the earth and, thus cannot completely cover the sun
(Moon further away due to orbital eccentricity)
What is a Lunar Eclipse?
When the shadow of the Earth obscures the moon
Why don’t Lunar Eclipses occur monthly?
The eccliptic planes of the sun and moon don’t allign much.
What is the length of time between Tides?
High→low is ≈6h
High→high is ≈12h
How much earlier do tides occur each day?
≈50 minutes
Due to the period of the Moon’s orbit
When do Spring Tides occur?
When the Sun and Moon are alligned with the Earth
Full or New Moon
When do Neap Tides occur?
When the Sun is 90° from the Moon
First or Last Quater
What is Precession?
The moving of the axis of rotation
A single precession on Earth lasts 26000 years
What is the Angular Diameter of the Sun?
≈ 0.5°
What is the Angular Diameter of the Moon?
≈ 0.5°
What is an Astronomical Unit?
The mean distance between the Earth and the Sun
150x10^8
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.
Which direction do the planets travel when viewed from the North Pole?
Anti-Clockwise (Prograde)
How does the Daily Motion of the Planets appear?
East→West (Prograde)
How does the Monthly Motion of the Planets appear?
West←East
Why can Superior Planets appear to have Retrograde Motion?
It is an illusion caused by Earth passing the Superior Planets in their orbit
What is an Inferior Planet?
A Planet closer to the Sun than Earth
What is a Superior Planet?
A Planet further from the Sun than Earth
What is Elongation?
The angle between a Planet and the sun when viewed from Earth
When are Superior Planets at greatest Elongation?
When on the opposite side of Earth to the Sun
180°
What is the greatest angle of Elongation of Venus?
47°
What is the greatest angle of Elongation of Mercury?
28°
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
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