Structure/Formation of Earth

Question 1

How old is the universe

Answer 1

13.8 Ga

Question 2

How old is the Earth

Answer 2

4.543 Ga

Question 3

Planet Differentiation

Answer 3

Process of creating concentric compositional shells within a rocky planet via gravitational sinking of molten metals (Iron) which forms the core of the planet.
Concentric Layers= Core, Mantle, Crust

Question 4

Which layer of the Earth is the magnetic field generated?

Answer 4

Outer Core

Question 5

4 Most common Elements on Earth

Answer 5

Silicon, Oxygen, Iron, Magnesium

Question 6

How does internal heating of Protoplanets occur? (3)

Answer 6

[Impacts]-Planetesimal collisions
[Compaction]-Squeeze matter into smaller volumes
[Radioactivity]- Radioactive Decay

Question 7

How were the lightest elements formed? (Hydrogen and Helium)

Answer 7

The Big Bang

Question 8

How are intermediate elements made?

Answer 8

Inside stars (Nuclear Fusion)
*combination of two lighter nuclei to form a new, heavier element
-> Releases heat needed to power stars
-> Nuclear Synthesis: generation of new, heavier elements

Question 9

How are heavy elements formed?

Answer 9

Super Nova Events

Question 10

What powers the Sun?

Answer 10

Hydrogen Fusion

Question 11

Moon Formation?

Answer 11

Occurred about 4.5 Ga
Formation Theory: Proto-Earth struck by planetesimal, knocking off debris that coagulated into what we know as the moon today. Because it was made up of the same proto-earth material, gravitational pull persists.
-Thought to be Molten and cooled over time
-Crust of Moon formed by crystals floating to the top of magma ocean (crust: plagioclase; Mantle: olivine and pyroxene)

Question 12

Chemical Composition of Earths Layers

Answer 12

Core: (Fe-Ni Alloy)
Crust + Mantle: Silicate

Question 13

Density of Earth

Answer 13

Lithosphere<Asthenosphere<Mantle<Outer Core< Inner Core

Question 14

How do we know Structure and Composition of Earth?

Answer 14

1.) Seismology
2.) Rock Samples
-Meteorites: Tell us about the beginning of time/ materials of the solar system
-Xenoliths: deduce makeup of Earths inner interior
(pieces of lower crust + mantle brought to Earth’s surface by volcanic eruptions)
-Tectonic Exposures: Lower crust/ upper mantle composition

Question 15

How was the Earth discovered to have a Core?

Answer 15

Seismological shadow zones

Question 16

P-Wave Shadow Zone

Answer 16

P-waves =compressional waves that travel through liquid
P-wave Shadow created by chemical difference of the core and mantle (Fe-Ni alloy vs Silicate)

Question 17

S-Wave Shadow Zone

Answer 17

S-Waves= Shear-waves which don’t travel through liquid
(we infer the core is liquid given p-waves travel through it and s-waves reflect)

Question 18

Lithosphere

Answer 18

Cold, Strong, Low Density

Question 19

Asthenosphere

Answer 19

Hot, weak, convecting, high density
-Mantle deforms plastically (flows) >1280

Question 20

Continental Crust Vs Oceanic

Answer 20

Continental:
-Higher Si content
-Thicker, more complex crust and Lithosphere
-older
Oceanic:
-Higher Mg content
-Thinner crust and lithosphere
-younger

Question 21

Where are volatile planets in relation to the sun

Answer 21

Furthest from the sun in the solar system

Question 22

Radioactive Decay: Half Life

Answer 22

1/2^x
x=# of half-lives

Question 23

A radioactive Isotope has a half-life of 1 billion years. After 5 half-lives how much of the origin parent material will be left?

Answer 23

2^5=32
Answer: 1/32