1. Planet Earth Flashcards
What is the shape of the Earth and why?
Oblate spheroid, because it’s polar diameter is 42 km smaller than it’s equatorial diameter
What is the mean diameter of the Earth?
13,000 km
How many major internal divisions does the Earth have, and what are they?
There are four: crust, mantle, outer core and inner core
What are the features of the crust?
The crust is very thin, ranging in thickness from 0 - 70 km. The continental crust is older and consists of low-density rocks such as granite. The oceanic crust is younger and thinner, and consists of darker, denser rocks such as basalt. The crust is split up into tectonic plates that float on top of the mantle
What are the features of the mantle?
The mantle extends halfway to the Earth’s centre and makes up ~80% of the Earth’s volume. The lower mantle is solid whereas the upper mantle is semi-molten, which allows thermal convection currents to rise and fall, which make the tectonic plates move
What are the features of the outer core?
The temperature is ~5000 K, and is made of liquid iron with some nickel. Currents of charged particles that flow in the outer core are responsible for the Earth’s magnetic field
What are the features of the inner core?
The temperature is ~5500 K, which is about the same temperature as the Sun’s photosphere, but the high pressure prevents the iron and nickel from melting
Latitude and longitude coordinate system
Latitude and longitude coordinate system
Latitude and longitude coordinate system
Latitude and longitude coordinate system
Latitude and longitude coordinate system
Latitude and longitude coordinate system
Equator
Prime meridian
Tropic of cancer
Tropic of Capricorn
Arctic circle
Antarctic circle
North pole
South Pole
What are the features of the Earth’s atmosphere?
It provides us with oxygen to breathe, absorbs harmful solar UV and X-radiation, regulates our planets temperature to a mean 15°C and protects us from most meteoroid strikes
How does the sky colour affect astronomical observations?
The sky is blue, as light is scattered by oxygen and nitrogen molecules in our atmosphere, and most scattering occurs at the shortest (blue) wavelengths, and so the sky is predominantly blue. This means making observations is restricted to nighttime
How does the stars ‘twinkling’ affect astronomical observations?
Air in the atmosphere is continuously in turbulent motion, as different densities of air rise and fall on a variety of scales, causing light to refract and change direction as it passes through the different layers. These adverse seeing conditions make the stars appear to ‘twinkle’
How does light pollution affect astronomical observations?
Skyglow is the rusty orange haze cast by lights near urban conurbations, and local glare from sports grounds, supermarket car parks; streetlights and security lights ruin our eyes’ night vision (dark adaptation)
