planet structure

lecture 1

current atmosphere gas composition

78% Nitrogen

21% Oxygen

1% trace gases

(0.9% Argon

0-5% water vapour

425ppm Carbon Dioxide

1800ppb Methane

340ppb Nitrus Oxide)

Inert

full electron shell, doesn’t interact with other atoms in order to get a stable structure.

monatomic vs diatomic

monatomic= single, stable unbonded atom, doesn’t bond.

diatomic= two unstable atoms chemically bonded together.

albedo

how reflective a surface is.

absorption of sunlight (infared) re-radiates into planet surface.

refraction of sunlight goes back into space.

order of atmosphere layers

(The Strong Mans Triceps Exploded)- separated by temp.

.Troposphere

.Stratosphere

.Mesosphere

.Thermosphere

.Exosphere

Hypsometric Curve

elevation of the planet surface against the % of the planet surface.

% of land vs surface water

30% land

70% surface water

cryosphere

ice covering the land and sea

avg ocean depth

40km

earth vs universe age

earth - 4.6bil

universe - 14bil

avg density of earth

5.5g cm -3

Core characteristcs

.Inner:

-composed of nickel&iron,

-solid under extreme pressure

-density >12g cm -3

-s&p waves move through.

.outer:

-less pressure

-composed of liquid due to lower density, iron, nickel & 10% lighter elements

-movement of iron generates the magnetic field- essential to most life on earth

-s waves can’t pass through, slows down p waves

mantle characteristics

.Thickest layer, divided into 2 sublayers (boundary due to changes in velocity of seismic waves that travel through.

.Lower mantle

-solid, made of stony, silicate material (same as stoney meteorites).

-density 5.5g cm -3

.upper mantle

-solid silicates but less dense (3.5g cm -3)

-part of upper mantle is within the asthenosphere and partly lithosphere.

asthenosphere

.most mantle behaves as solid with ability to flow very slowly (rheid), about 10-15cm year -1 (depending on which plate)

.upper mantle within asthe and litho

.asthe is semi solid, partial melting of minerals allows it to flow, convection.

lithosphere

.rigid and brittle (too cold, wax analogy).

.carried by asthe, broken into plates that change over time

.outermost skin of litho is crust (oceanic or continental), divided by moho.

Moho (andrija mohorovicic)

physicist who discovered the velocity of p waves increased at a depth of about 50km (varies depending on type of crust), change in rock.

-identified presence of litho

-nearby seismographs found p waves travelled the shallow path through the crust and moved more slowly

-further away seismographs found p waves travelled a deeper path through the mantle and travelled faster

crust characteristics

.oceanic

-thinnest (7-10km)

-avg density 2.9g cm-3

-largely basalt

.continental

-thickest (25-70km)

-avg density 2.7g cm-3

-avg granite

47% oxygen

28% silicon

8% aluminium

3.5% calcium

4.5% iron

9%others

2 types of meteorite

metallic

-density 7-8g cm-3

-composed of iron, nickel, some sulphur minerals, similar to our core.

stony

-density 3-3.7g cm-3

-composed of silicate minerals, similar to earths mantle.