planet
EARTH
Characteristics of the Earth:
1)shape = oblate sphere
2)Earth is tilted on its axis
3)Earth ROTATES around its AXIS
*** 24 hrs = 1 rotation
4)Earth REVOLVES around the SUN
*** 365.4 days = 1 revolution
5)Earth is covered in 71% water
6)Circumference at the equator
= 40,074 kilometers (km)
7)Circumference from pole to pole
= 40,007 km
The Earth’s Layers
1)Crust –
2 kinds: oceanic crust – under the ocean
Continental crust –
land masses
2)Lithosphere – broken into plates; appr. 30 plates
3)Asthenosphere – “plastic rock”
i.Under pressure = hard as a rock
ii.Low/no pressure = flows as a liquid – the plates of the lithosphere ride on the asthenosphere to move
-when 2 plates separate, the liquid asthenosphere will fill the gap
SO...
**** when 2 plates separate = DIVERGENT boundary (valley can be formed this way)
*** when 2 plates come together = CONVERGENT boundary (mountains are formed this way) ALSO HAVE SUBDUCTION – 1 plate goes beneath the other plate
DENSITY KEY FACTOR in the movement of the plates
And then..
4)MESOSPHERE – solid rock layer
5)Outer Core – we think it is a dense liquid (IRON)
6)Inner Core - we think it is a dense solid
Mantle:
- Lithosphere
- Asthenosphere
- Mesosphere
Photo credits: 'horizon' by pierreyves @ flickr