L1-3 earth and space

Question 1

Origin of hydrogen

Answer 1

Process: big bang
Location: expanding universe

Question 2

Origin of helium

Answer 2

Process: proton - proton chain
Location: “main sequence” stars during 90% of their lives

Question 3

Origin of carbon nitrogen and oxygen

Answer 3

Process: CNO cycle
Location: depleted H leads to temp rises and He gains the ability to merge in “main sequence” stars

Question 4

Origin of extra carbon

Answer 4

Process: triple alpha process
Location: once H becomes depleted in “main sequence” stars

Question 5

Origin of elements up to iron

Answer 5

Process: not given
Location: the death of large stars

Question 6

Origin of elements between iron and bismuth

Answer 6

Process: s-process (the slow addition of neutrons
Location: supergiant stars

Question 7

Origin of neutron rich elements eg uranium and thorium

Answer 7

Process: r-process (the rapid addition of neutrons)
Location: supernovae

Question 8

Origin of Sun

Answer 8

A gravitational collapse which resulted in a spinning hot gas nebula.
Most matter collapses into sun and fusion begins.

Question 9

Origin of planets

Answer 9

Remainder of nebula which collapsed to form sun cools and begins to separate according to condensation temperature

Question 10

Describe two kinds of planets and how they form

Answer 10

Rocky planets: metals and silicates condense at high temperatures meaning they predominantly form closer to the sun. Accretion then occurs through collisions.

Gas and ice planets: volatiles only condense at low temperatures so volatile rich planets form further out from the sun. Accretion then occurs through collisions.

Question 11

Evidence for the formation of the galaxy

Answer 11

Observation of other stars
Meteorites - chondrites (combinations of metals silicates and volatiles) and achondritic and iron (remains of planetoids)

Question 12

Structure, density and composition of earths interior

Answer 12

Crust: thin outer layer. predominantly made up of Na-Ca-Al silicates. 3.3 g/cm3

Mantle: 2d = 50%, 3d = 84%. predominantly made up of Mg-Fe silicates. 4.4 g/cm3

Outer core: 2d = 66.66% of core, 3d = 16% collectively. 12 g/cm3 collectively.

Inner core: 2d = 33.33% of core, 3d = 16% collectively. 12g/cm3 collectively.

Earth as a whole: 5.5 g/cm3

Question 13

Principal sources of information about earths interior

Answer 13

Seismic waves: p waves travel faster and velocity is distorted by moving through different states while s waves travel slower and cannot travel through liquids. therefore, we know that the outer core is liquid

Meteorites:
Chondrites - most abundant, metal and volatile rich, oldest objects in solar system “starting stuff”
Achondrites - metal and volatile poor, younger then chondrites, silicates from the mantle of planetoids, some from mars and the moon, post differentiation part of mantle
Iron meteorites - metal rich samples of core of planetoids

Acceleration due to gravity: acceleration can be used to calculate mass and mass / volume = density. this means that we figure out the approximate relative densities of layers

Question 14

Formation of earths interior

Answer 14

Earths interior was molten so material was separated according to density.
Fe-Ni metal as the densest sunk to core
Mg-Fe silicate was layered on top of this
Na-Ca-Al was layered on top of that

Question 15

Thickness, composition, age and density of oceanic and continental crust

Answer 15

Thickness
Continental crust - 25-60 km ave. 35 km
Oceanic crust - 5-10 km ave. 7 km
Composition
Continental crust - Sedimentary, metamorphic and rhyolites or granites
Oceanic crust - basalt with a sedimentary cover
Age
Continental crust - all of earths history
Oceanic crust - 200 ma
Density
Continental crust - 2.7 g/cm3
Oceanic crust - 3 g/cm3

Question 16

Differences between lithosphere asthenosphere and crust mantle

Answer 16

Lithosphere-asthenosphere: deformation behavior is what delineates the two - the lithosphere will crack where as the asthenosphere is malleable. the relationship is NOT defined by composition

Crust-mantle: composition delineates the two - mantle is mainly Mg-Fe silicates while the crust is Na-Ca-Al silicate based

Question 17

Basic plate tectonic boundaries and how they operate

Answer 17

Divergent boundary: spreading, often mid ocean ridges but can occur continentally as well

Convergent boundary:
Subduction - one plate subducts under the other. causes volcanic belts. occurs with plates of different densities
Collision - both plates collide pushing each other up. causes mountains. occurs when plates are similar densities

Transform boundary: plates move from side to side

Question 18

Principal sources of energy that drive Earth processes

Answer 18

Convection traction: convection currents pulling the plates with them
Slab pull: subducting plates pull down
Ridge push: ridges push out