Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

astro > astro 4 > Flashcards

astro 4 Flashcards

1
Q

did the terrestrial planets all look quite similar last time

A

The surfaces of all 5 terrestrial worlds (Mercury, Venus, Earth,
Moon, Mars) must have looked quite similar when they were
young, and all were subjected early on to the Heavy Bombardment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How did the terrestrial inner worlds ended up so different although
they were made similarly from metal and rock that had condensed in
the initial solar nebula?

A

Their current appearances must be the result of changes that
occurred after their formation & initial ‘childhood’ (i.e. due to
their planetary evolution).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

do all the terrestrial worlds have the same type of distinct

layering

A

g due to (at some time in the past) differentiation
= process where gravity separates materials by density -> ALL terrestrial planets must once have been hot enough for
the interior rocks & metal to melt
& separate by density

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

The interiors of any terrestrial planet is divided into 3 major layers

A

Core: made of the highest density materials (e.g. Ni, Fe)
Mantle: made of rocky material of moderate density
(minerals containing mainly Si, Mg, O)
Crust: made of rocky material of lowest density, e.g. granite
& basalt (volcanic rocks)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is granite

A

Granite is a course-grained rock
composed mostly of quartz and solidifies
underground

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is basalt

A

Basalt is a fine-grained rock rich in Mg &
Fe exposed at or very near the surface of a
rocky planet or a moon. More than 90% of
all volcanic rock on Earth is basalt

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

which is denser & heavier, basalt or granite

A

Basalt

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is the rigid lithosphere

A

crust and part of mantle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what are the layers of earth in order

A

rocky crust>rigid lithosphere > mantle > metal core

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

The outermost rigid part of a planet is called

A

lithosphere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what generally encompasses the crust and part of the mantle

A

lithosphere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is The upper layer of the mantle right below the lithosphere

A

asthenosphere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

asthenosphere

A

It has relatively low resistance to plastic flow as it is hotter
and more fluid and this is where convection is thought to occur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what thickness is closely related to planetary size!

A

Lithospheric thickness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

 Small worlds tend to have thicker

A

=lithospheres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why are planets round?

A

Rocks deform & flow under high
p and/or T, and the gravitational field originating from the center acts
equally in all directions and pulls everything toward it, ultimately
smoothing out the shape into a sphere.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

 The weak gravity of a small object is

A

s unable to overcome the rigidity of its

solid material clustered together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Within 1b y gravity will make into a sphere

A

any object bigger than ~500 km in diam.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Geological activity

A

the process of ongoing changes in the surface & structure of a planet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Why were the planets hot? What is/was the source of this energy?

A

3 sources of energy for the internal heat of terrestrial worlds:
 Heat of accretion
Differentiation
Radioactive decay (fission

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Heat of accretion

A

Gravitational potential energy of a planetisimal is converted into kinetic energy
which, upon impact, is converted into heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Differentiation

A

Release of additional heat as dense
materials sank to core and convert their
gravitational potential energy into heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

 Radioactive decay (fission)

A

Radioactive isotopes (U, Th, K) convert
their mass-energy (E=mc
2) into heat
 Declines in time —>much more significant
when planets are big and/or young
 Still
supplies heat to the terrestrial interiors but
at a lower level than when the planets were young.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How interiors cool off

A

convection, conduction, radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

e most important factor

in planetary cooling.

A

size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

 Convection:

A

heat transported upward as hot material expands &
rises, dissipates energy at the outermost surface, then cooler
material contracts & falls
 Occurs if the heating source is below

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Conduction:

A

heat transfer from a hot material/region to a cooler
one through contact
 Due to microscopic collisions of their constituent particles (atoms/molecules)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Radiation:

A

Thermal radiation carries
energy away from object
 Planck’s law: ANY blackbody emits radiation
characteristic of their temp. T
 Because of their low T, planets emit in IR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Large planets retain

A

n internal heat much

longer than smaller ones!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Lithosphere grows thicker

A

as planet’s interior cools.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

what is the primary driver of geological activity

A

Interior heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

most important heat transfer process of Earth

A

Convection thru convection cells within the mantle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Mantle convection primarily involves

A

solid rock(not molten rock)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

how long does mantle convection take

A

is a very slow process (a few cm/year!, i.e. a full cycle takes ~500m y)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

The mantle is made of solid rock because

A

after Earth’s
formation it cooled over
m of years. Water trapped inside
minerals erupted with lava, a process called “outgassing—>the mantle solidified.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Mantle convection stops at

A

the base of lithosphere.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

why does Mantle convection stop at the base of lithosphere.

A

Heat dissipates upwards primarily through conduction,
then radiates away into space once it reach Earth’s surface
 Primary driving force for the movement of the tectonic
plates = the pieces into which the lithosphere is broken
 Lava erupting from volcanoes comes only from a narrow
region of partially molten material beneath the lithosphere.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Planetary size determines

A

the strength of mantle

convection & lithospheric thickness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Venus is probably similar to Earth in

A

n its internal

heat & nearly as geologically active as Earth.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

what is the problem on venus lol

A

 Problem: lack of water, which on Earth (incorporated in many minerals, e.g. olivine) acts as lubricant and eases
tectonic plate movements.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

The Moon has a very thick lithosphere & no

geological activity due to

A

its small size

42
Q

Mercury also cooled quickly but

A

may still retain some heat in its very large core.

43
Q

Mars, intermediate in size, has cooled

significantly but

A

probably retains enough internal heat for some reduced geological activity.

44
Q

Why do some planetary interiors create a magnetic field?

A 
Interior heat plays another crucial role: it can create a global
magnetic field (MF) → creates a magnetosphere.
45
Q

3 basic requirements to generate a global magnetic field (MF):

A

 An interior region of electrically conducting fluid (gas/liquid, e.g. molten
metal)
 Convection in that layer of fluid
 At least moderately rapid rotation around its axis.

46
Q

 Earth = the only terrestrial world that meets ALL 3 BASIC requirements

A

Dynamo effect: Earth’s MF is due to

convection in the liquid outer core AND the Coriolis force due to Earth’s rotation

47
Q

The Coriolis force tends to o

A

organize the flow within the outer core

into rolls aligned along the N-S polar axis.

48
Q

None of the other terrestrial planets has

A

a MF as strong as Earth’s

49
Q

 Electrons

(e–) in molten metal move within the outer core ________________

A

similar to the current flowing thru an electromagnet but in a self-sustaining
process.

50
Q

Why do some planetary interiors create a magnetic field? Moon:

A

core has long since cooled & stopped convecting  no MF

51
Q

Why do some planetary interiors create a magnetic field? Mars

A

: Its core (part of mantle too??) probably still retains some heat, but not enough to drive core convection, hence it lacks a MF.

52
Q

Why do some planetary interiors create a magnetic field? Venus

A

: probably has a molten core similar to Earth’s, but either its convection or very slow rotation is/are too weak to generate a MF

53
Q

Why do some planetary interiors create a magnetic field? Mercury

A

an enigma as it does have a MF despite its small size &
slow rotation → most probably due to a huge core that may still
be partially molten and convecting.

54
Q

Why do some planetary interiors create a magnetic field? Jupiter

A

has a very strong MF due to a layer of convecting metallic hydrogen & its rapid rotation.

55
Q

Why do some planetary interiors create a magnetic field? Jupiter

A

At same planetary size, a molten metal layer generates a stronger MF
than an ionic liquid

56
Q

Why do some planetary interiors create a magnetic field?  Sun:

A

its MF is due to convection of ionized gas (plasma) & its

rotation.

57
Q

A planet’s MF creates a

A

magnetosphere = a region of space
surrounding an astronomical object in which charged particles
are affected by that object’s magnetic field.

58
Q

A magnetosphere acts as a

A

protective bubble which deflects

most of the charged particles in the solar wind

59
Q

If the (Earth’s) magnetosphere were not present (or weak),

A

highly energetic particles can strip away atmospheric gases & cause genetic damage to living organisms.

60
Q

ALL surface features on a terrestrial planet (e.g. on

Earth) are caused by just 4 major processes

A

Impact cratering:
Volcanism:
Tectonics:
Erosion:

61
Q

Impact cratering:

A

excavation of bowlshaped craters by asteroids or comets

crashing into the surface

62
Q

Volcanism:

A

eruption of molten rock, or
lava, from its interior onto its surface
 Some planets may have instead cryovolcanism, in
which volatiles/liquefied gases (e.g. H2O, NH3,
CH4) are ejected instead of lava

63
Q

Tectonics:

A

building/reshaping of surface
features due to stretching, compression or
other forces acting on the lithosphere

64
Q

Erosion:

A

wearing down or building up of
geological features by wind, water, ice &
other planetary weather

65
Q

Cratering

A

An impact crater forms when an
asteroid/comet slams into a solid surface

Many impact craters on Earth & other worlds,
especially Moon & Mercury.

Earth bombarded by impacts when it was young,
but most ancient craters were erased by
volcanic/geological activity & erosion

 Craters can provide very important clues:

66
Q

An impact crater forms when an

asteroid/comet slams into a solid surface.

A

 The released energy vaporizes rock and blasts out a
crater
= circular since material is ejected uniformly
in all directions (for normal incidence!)

67
Q

Many impact craters on Earth & other worlds,

especially Moon & Mercury.

A

 Most cratering happened soon after the Solar system
formed (2 episodes of Heavy Bombardment).
 Small craters far outnumber large ones
 many more
small objects than large ones in the initial solar nebula

68
Q

 Craters can provide very important clues:

A

The more craters, the older the surface.

 The geological conditions existent at the time of impact

69
Q

Volcanism

A

Volcanism occurs when underground molten rock (magma) finds a path to the surface through the lithosphere

Volcanism produces volcanic mountains & explains the
existence of our atmosphere & oceans.

70
Q

Volcanism occurs when underground molten rock (magma)

finds a path to the surface through the lithosphere

A 
Molten rock/magma = lower density
 rises with respect to
surrounding high density materials
 The solid rock surrounding a magma chamber can squeeze it, driving it
upward under pressure
 Magma often contains trapped gases that expand as it rises

dramatic & violent explosive eruptions
71
Q

 Volcanism produces volcanic mountains & explains the

existence of our atmosphere & oceans.

A

Water/ices originated from icy planetesimals, the rock from the
asteroids & planetesimals whose merger made up the planet. The
subsequent heavy bombardments may also have contributed
significantly, especially with water/ice.
 Volcanic eruptions release some of the initially incorporated
gases/liquids (outgassing)  made Earth’s atmosphere & oceans.

72
Q

Cryovolcanism: v

A

volcanism that may take place on cold worlds covered by ices (provided that an internal heat source is present).

Molten rock/magma is called lava after it reaches the surface.
 Lava can shape 3 different types of volcanic features, depending on its viscosity:

73
Q

Lava can shape 3 different types of volcanic features,

depending on its viscosity:

A

Runny lava (i.e. with the lowest viscosity) makes flat lava plains.
 Slightly thicker (i.e. more viscous) lava makes broad shield volcanoes.
 The thickest (i.e. most viscous) lavas solidify very quickly and make
steep stratovolcanoes

74
Q

Tectonics

A 
building/disruption of surface features by internal
stresses caused (directly or indirectly) by convection in the
underlying mantle.
75
Q

Tectonics =

A

Compression forces where adjacent convection cells push rock together —> mountain ranges
 Cracks & valleys form where adjacent convection cells pull the crust apart

76
Q

The stresses due to underlying mantle convection

A

fractured Earth’s

lithosphere into more than a dozen pieces called plates

77
Q

plates

A

 Plates move over, under & around each other → plate tectonics

78
Q

Only Earth has

A

plate tectonics

79
Q

what generally occur together

A

Tectonics & volcanism generally occur together—> heat

80
Q

Erosion

A

refers to weather-driven processes that break down or

transport rock through action of ice, liquid, or gas.

81
Q

Erosion

A

Shaping of valleys by the flow of ice bodies (glaciers).
 Carving of canyons by the flow of liquid water bodies (rivers).
 Shifting of sand dunes by winds (gas).

82
Q

Erosion can also

A

build up geological features
 Sand dunes, river deltas, lake bed deposits, accumulation of sediments into
layers on ocean floors -> sedimentary rocks.

83
Q

Atmosphere

A

 In most cases it is a surprisingly thin layer (compared to the size of the world)
 Can be a mixture of many different gases that may consist of individual atoms or of molecules.

84
Q

The collisions of individual atoms/molecules in an atmosphere create pressure

A

 Ideal Gas Law equation: pV = NRT, where p & V = the pressure &
the volume of the gas, N = the number of moles of gas, R = the universal gas
constant, and T = the absolute temperature.
 The gas in an atmosphere is held down by gravity.
 The collision-resulting pressure acts uniformly, pushing in all directions,
including upwards, making the atmosphere expand
 Planetary
atmospheres exist in balance between the downward weight of the gases &
upward push of their gases.

p↓ with↑ altitude H→ because air density ρ↓: p=ρTR/M, with M = molar mass.

85
Q

An atmosphere can have several key effects onto its planet:

A

 Its pressure (& temperature) determines if liquid (water) can exist on the
surface.
 Absorbs and scatters light.
 Creates wind & weather.
 Aurora is produced when the solar wind particles trapped in the
magnetosphere make it through & collide with atoms/molecules in the
atmosphere.
 Can make planetary surfaces warmer via the greenhouse effect.

86
Q

The greenhouse effect occurs only when

A

an atmosphere contains
gases that can absorb IR light (e.g., H2O vapor, CO2, CH4)
radiated back from the planet surface.

87
Q

The energy of an absorbed IR photon is not retained for long but

A

re-emitted as another IR photon, which is again absorbed by another molecule, etc., etc.
 greenhouse gases significantly slow down the escape of IR radiation
from a lower atmosphere, while the molecular motions of the latter’s
molecules heat it up (and also the planet’s surface)
 The greenhouse effect does NOT alter a planet’s overall energy balance

88
Q

Earth’s atmosphere consists of

A

77% N2, 21% O2 & small

amounts of other gases

89
Q

 Earth’s atmosphere consists of 77% N2, 21% O2 & small

amounts of other gases.and what does that cause

A

 Enables presence of liquid water = explains extensive erosion on Earth
 Sustains Life: without it, Earth’s surface would be lifeless due to the
dangerous solar radiation & so cold that all water were frozen

90
Q

 Earth’s atmosphere is

A

~480 km thick but ⅔ of our atmospheric
air lies within 10 km of surface (90% below 16 km)!
 Still other higher layers have vital roles (O 3 layer to block UV, absorption of X-rays)

91
Q

Earth’s atmosphere has 5 basic

layers/regions:

A

Troposphere Stratosphere Mesosphere Thermosphere Exosphere

92
Q

Troposphere =

A

= the lowest layer; here T↓ with↑ altitude H;

93
Q

Stratosphere=

A

composed of
stratified temperature layers; it
begins where T↑ with↑H, due to UV absorption by ozone (O3);

94
Q

Mesosphere =

A

= the region where T↓ again with↑ altitude H:
 The stratosphere and the mesosphere are sometimes collectively
referred to as the “middle atmosphere”

95
Q

Thermosphere =

A

= begins where T again↑ with↑ altitude H;

96
Q

Exosphere =

A

the uppermost region where the atmosphere gradually fades into space.
The layering is shaped by the way each region interacts with various
wavelengths of light

97
Q

Exosphere

A

 Heated by solar UV & X-rays
 Fast-moving gas molecules
can escape to space

98
Q

 Thermosphere

A

 X-rays heat & ionize gases

99
Q

 Ionosphere

A 
Made of ions created
by energetic particles
from solar wind and
outer space
 Reflects radio waves
and solar wind
 Comprises 4 layers (D,
E, F1, F2)
100
Q

Stratosphere

A

Heated by UV, layered, no convection

101
Q

Troposphere

A

Greenhouse gases trap IR
radiation from the ground
 Convection important

astro (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions