1. Planet Earth Flashcards
What shape is the Earth? Describe it
- Oblate spheroid
- A sphere like but not perfectly spherical body (slight squish; flattens at poles, bulges at equator)
What are the layers of the Earth?
Crust
Mantle
Outer Core
Inner Core
What are the features of the Crust?
- 55°c
- 0-70km
- rock, granite, basalt
What are the features of the Mantle?
- 650-800°c
- 2900km
- rock, mg, al, silver
- thick, almost solid liquid
What are the features of the Outer Core?
- 5000°c
- 2200km
- liquid rock/iron
What are the features of the Inner Core?
- 5500°c
- 1220km
- iron
- hot dense ball, pressure of 3.6mil atmospheres
What is Longitude?
Vertical lines telling us how far E or W a point is relevant to the prime meridian
What is Latitude?
Parallel lines telling us how far N or S a point is, relevant to the equator
What is the Prime Meridian?
A line (goes through Greenwich) that divides the Earth into E and W hemispheres
Time zones are determined by how far E or W you are
Where is the Tropic of Cancer?
Northern Hemisphere
23.5°N
Where is the Tropic of Capricorn?
Southern Hemisphere
23.5°S
What is the tilt of the Earth?
23.5°
Why do stars twinkle?
As light is passed through the layers in the atmosphere it is bent and distorted by the varying temperatures and air densities
These seeing conditions make the stars ‘twinkle’
What does atmospheric scintillation mean?
Stars Twinklings
- The quick changes in the brightness of a star produced by atmospheric effects
Why don’t planets twinkle?
Stars are so much further away & are concentrated points of light, which are more easily disrupted by the Earth’s atmosphere
What is the atmosphere like above the equator?
There is a low pressure zone called the intertropical convergance zone - a wide belt of trade winds and rising air
Areas above/next to the equator have frequent cloudiness and thunderstorms
When is the sun directly above the Tropics?
Cancer - Noon, June 21st
Capricorn - Noon, December 21st
When do the equinoxes occur?
When the sun is directly over the equator
When is the arctic circle dark?
The Winter Solstice - sun won’t be able to be seen at all
AC = Latitude 66.5°N
How can the Earth’s atmosphere affect observations?
- Temperature changes
- Air currents
- Weather fronts
- Dust particles
(all can affect the transparency of sky) - Blue sky - obs can only be done at night
Why does the sky appear blue?
Light is scattered by oxygen and nitrogen molecules in our atmosphere, most scattering occurs at the shortest wavelengths (blue) so the sky is predominantly blue
What are the layers of the Earth’s atmosphere?
- Troposphere
- Stratosphere
- Mesosphere
- Thermosphere
- Exosphere
