oblate spheroid
a sphere flattened along the axis from pole to pole such that there is a bulge around the equator
mean diameter of earth
13,000 km
internal divisons of earth
crust, mantle, outer core, inner core
features of crust
outermost layer with oceanic (5-7km) and continental (30-50km) crusts. the temperature at mantle edge is 200 - 400km
features of mantle
extends down from the surface to 2900 km (thickest layer), the upper mantle where temp is cooler with composition being solid rock and lower mantle with 80km depth, temp increases to 1400 and rock becomes molten
features of outer core
made up mainly of iron and nickel but temperatures are so high that this core is very dense molten metal
features of inner core
temperatures of 4,400 to 6,600, however metals remain in a solid state due to immense pressure created by the weight of outer core and mantle
latitude
measure of how many degrees north or south of the equator a point is
longitude
measure of how many degrees east or west of the prime meridian a point is
blue sky
as white light passes through atmosphere, air molecules cause it to scatter. as scattering increases, wavelength of light decreases. violet/ blue light has the shortest wavelength causing more blue light to be scattered and sky appearing blue
skyglow
diffuse luminance of the night sky, a commonly noticed aspect of light pollution
causes of light pollution
outdoor lights, advertisements, factories, satdiums
seeing
antoniadi scale
measure of the effect of atmospheric motions on an image (usually of moon or planet)