Sem#2 Chap 9 Flashcards
1
Q
Solar Storm
A
Sun emitted billions of tons of charged particles
* Protons, electrons, and helium nuclei
* Traveled through space at 1.6 million km/h
2
Q
Society must consider risks
from outer space: List them:
A
- Space weather from the Sun
- Asteroid and comet impacts
3
Q
Fusion reactions combine _____ to form _______.
A
hydrogen to form helium.
4
Q
Matter exists as ______on Sun
A
plasma
5
Q
Plasma
A
- Hydrogen and helium atoms without their electrons
- Free electrons
6
Q
Corona
A
The top of solar atmosphere
7
Q
Solar wind
A
Corona’s plasma that escapes the Sun’s gravity
8
Q
Solar plasma particles
A
- Travel ~400 -750 km/s
- Reach Earth’s orbit in 2.3 to
4.3 days - Density is ~5 particles/cm3
9
Q
Electrically charged particles create a ______.
A
magnetic field
10
Q
Sunspots appear as ______. (physical looks)
A
dark patches
11
Q
Sun’s magnetic field reverses
polarity once every ______.
A
11 years.
- Field strengthens and
weakens within this period
12
Q
A magnetic field has two
poles. List them:
A
(north and south).
13
Q
Field lines arc into space
when ________.
A
field is strong.
- Plasma upwelling is slowed.
- Cooler patches develop.
14
Q
Plasma Arc (look like )
A
Slide #9 Chap 9
15
Q
Prominences:
A
- Release glowing gas and plasma
- Arc from one sunspot to another, within a pair
- Arcing magnetic field lines become visible.
- Last hours, days, or weeks
16
Q
Flares
A
- Release large amounts of electromagnetic energy
- Last minutes to hours
17
Q
Flares may disrupt _______.
A
Earth’s atmosphere
Radio waves disruption is
likely.
18
Q
CMEs:
A
- Release plasma into space
- Plasma travels faster than
typical solar wind. - CME plasma speed can reach
~3,000 km/s.
19
Q
CMEs affect Earth if _______-.
A
planet is within plasma’s path
- Disturbances in Earth’s magnetic field are likely.
- Severe space weather is likely.
- Human activities are at risk.
20
Q
Class Question #1
How is a solar flare different from a coronal mass ejection?
a) A solar flare expels electromagnetic radiation into space, while a
coronal mass ejection expels plasma.
b) A solar flare’s plasma travels at the speed of light, while plasma
from a coronal mass ejection travels at the speed of sound.
c) Solar flares are expelled from the sun’s convective zone, while
coronal mass ejections are expelled from the sun’s core.
d) Solar flares create space weather within the Sun’s atmosphere,
while coronal mass ejections create space weather in Earth’s
atmosphere.
A
(NOT GIVEN)
21
Q
3 types of ultraviolet (UV)
radiation:
A
UV-A; UV-B; UV-C
22
Q
Some UV-A and UV-B reach
Earth’s surface. Affects people how?
A
Cause skin damage, wrinkles, and sunburns
23
Q
The stratosphere stops ______ (radiation).
A
UV-C
24
Q
_______ breaks molecular bonds
in stratospheric O2
A
UV-C
- Creates free oxygen atoms
- O and O2 merge to form O3.
25
Ozone (O3):
* Mostly in stratosphere
* Absorbs UV-C radiation
* Protects Earth’s surface from
harmful, high-energy UV-C
26
Chlorofluorocarbons (CFCs)
break up ______.
O3 molecules
27
Ozone hole:
a region of reduced stratospheric ozone
* Mostly over Antarctica
* Global O3 reductions occur
due to worldwide air mixing.
* More UV-A and UV-B reach
Earth’s surface.
* Skin cancer risk increases.
28
Earth’s outer core consists of
rotating______.
liquid iron
Rotating liquid metal
generates a magnetic field.
29
Solar wind distorts field into a _____ shape.
teardrop
Magnetotail points away
from Sun.
30
Magnetic field shields Earth
from ______.
solar wind
31
Magnetosphere
the region inside the magnetic shield
32
Solar wind creates electric
currents in _______.
magnetosphere
33
Van Allen radiation belts
* 1,000 and 12,000 km from
Earth
* Ions oscillate rapidly back
and forth between poles.
34
Aurorae:
* Develop as solar wind electrons descend over poles
* Electrons excite atmospheric gases, creating gauzy lights.
* Aurora Borealis is over the northern pole.
* Aurora Australis is over the South Pole.
35
Heating of the thermosphere:
* Solar wind and radiation heat up thermosphere’s gasses.
* Thermosphere expands into region where satellites orbit.
* Satellite orbits become less predictable.
36
Radio transmissions disruption:
* Modern communications depend on radio waves.
* Satellites, cell phones, and the global positioning system (GPS)
37
Electrical Currents can damage???
Electrical discharges can damage satellites.
Rogue electric currents can disrupt power grids.
* In 1989, a solar storm blacked out Quebec’s grid.
* Cascading failure is possible, since most grids are connected.
Rogue electric currents can damage electronic equipment.
38
Mitigating Space Weather
* Electronic equipment can be radiation hardened.
* Electric grids can be designed to stop surges.
* Power companies can stage replacement equipment.
* Equipment can be shut off before space weather arrives.
39
The Space Weather Prediction Center:
* Watches for solar storms
* Issues warning to utilities and governments
40
Class Question #2
Why is the magnetosphere important?
a) It shields Earth from UV-A and UV-B radiation.
b) It heats up the thermosphere, thereby ensuring that satellite orbits
remain stable and predictable.
c) It shields Earth from hydrogen and helium atoms, as well as from
free electrons, emitted from the Sun.
d) It stops aurorae from forming over the South Pole.
(NOT GIVEN)
41
Asteroids:
rocky or metallic objects mostly in asteroid belt
42
Comets:
ice and rock masses from the Kuiper Belt, or beyond
43
Meteoroids:
rocky or metallic objects traveling through space
44
Planets, moons, and dwarf planets pose ____ threat to Earth.
no
45
Kuiper Belt contains ______ outside ______ orbit.
icy objects outside Neptune’s
46
Most space objects vaporize in ______.
Earth’s atmosphere
47
Extinction-level event:
* Threatens the existence of life on Earth
48
Coma
ionized gas around a comet’s solid nucleus
49
Short-period comets have
orbits ______ years.
<200
50
Long-period comets have
orbits ______ years.
>200
51
Slide #42 go back a few and look at images
readdddd
52
Meteoroids Size:
small objects with diameters <100 m
53
Meteorites:
meteoroid remnants on Earth’s surface
54
Stony meteorites:
* 93% of all meteorites
* Mostly silicate rock
* Chondrites have chondrules
(colorful, round fragments)
55
Chondrite
a type of stony meteorite
56
Iron meteorites: (Made of?)
Made of iron-nickel alloy
57
Stony-iron meteorites: Are made up of , list:
Contain metal and rock
58
Meteorite falls:
* Found beneath where a
meteor was observed
* ~1,180 have been found
* Largest fall occurred in 1947
in Russia (23,000 kg).
59
Meteorite finds:
* Found at old impact sites
* Largest find occurred in
1920 in Namibia (66,000 kg).
60
Look at images on slide 44-45
reeadsadaads
61
Good locations to look
for meteorites:
* Deserts
* Farm fields
* Antarctica and
Greenland ice sheets
62
Cosmic speed:
the speed of a meteoroid relative to Earth
* 11–72 km/s
63
Ram compression:
* Occurs when a meteoroid
compresses air in its path
* Air heats to ~1,700°C.
* A skin of melt and hot rock
spalls off meteoroid.
64
Meteors are streaks of light from
_________.
glowing vapor and dust
65
Meteors are often misnamed ________.
shooting stars
66
Meteor showers display ~____–____meteors per hour.
10–100
67
Meteor storms display ~_____ meteors per hour
1,000
68
Bolides are _______.
explosions
* Produce shock waves and
sonic booms
69
Weight and size partially
determine impact speed:
* <7,000 kg, or <1 m in
diameter, impacts at ~500
km/h
* >1,000,000 kg, or ~4 m in
diameter, impacts at ~70%
cosmic speed
* >1,000,000 kg, or >15 m in
diameter, impacts at cosmic
speed
70
Lunar impacts are often observed with _____.
telescopes
71
Class Question #3
What is a meteor?
a) loose rock, dust, and ice aggregates with highly elliptical orbits
b) small objects moving through space with diameters <100 m
c) icy objects located outside the Kuiper Belt
d) streaks of light from glowing hot gas and dust
(NOT GIVEN)
72
Crater character depends on several variables.
* Size, density, and coherence of meteorite
* Impact velocity and angle
* Composition of planetary surface
73
Small, slow meteorites produce craters ___ times their diameter.
< 8
74
Large, fast meteorites produce craters___ their diameter
~16+
75
Excavation stage:
* Target rock shatters, and
ejecta is created.
* Target rock is fractured
beneath impact site.
* Impact melt may be created.
* Transient crater is created.
76
Modification stage:
* Transient crater rebounds.
* Raised rim appears.
* Impact breccia and ejecta
blanket cover rim.
* Pseudotachylyte may appear
from solidifying melt.
77
Formation of Complex Craters
Rock beneath impact breaks,
heats up, and liquefies.
Modification stage:
* Central uplift occurs.
* Steeply tilted faults develop.
Impact melt quickly solidifies
into a flat crater floor.
Marginal terraces ring crater
due to faulting.
Slump blocks appear as
terracing and faults settle.
78
Astroblemes
Recognizable, ancient and
eroded impact structures
Many faults run parallel to the
crater’s rim.
Steeply tilted, central uplift
rocks are often discovered.
Numerous fractures and
brecciation are present.
Pseudotachylyte fills pores
within impact breccia.
Bedrock contains many shatter
cones.
Shock metamorphism forms
minerals coesite and stishovite.
79
Metamorphism Transforms Quartz into
Denser Minerals: List
Quartz: density: 2.62
Coesite: density: 2.91
Stishovite: density: 4.29
80
The Moon has ____ craters
with diameters ____ km.
~5,200
diameters >29 km.
81
Earth processes destroy or
hide most impact sites.: List them:
* Plate tectonics subduct
seafloor craters.
* Mountain building destroys
craters.
* Erosion erases craters from
Earth’s surface.
* Sediment buries craters.
82
Class Question #4
Identify the economic consequences of the asteroid impact that created
the Sudbury Basin, Ontario.
a) The impact created the Hudson Bay, which is home to a billiondollar Canadian fishing industry.
b) The impact created hundreds of billions of dollars worth of nickel,
copper, gold, and silver ore.
c) The impact nearly destroyed the city of Toronto and its surrounding
industrialized hinterland.
d) The impact initiated the formation of Canada’s petroleum and gas
deposits.
(NO GIVEN ANSWER)
83
Extinction:
marks the death of a species’ last organism
84
Mass extinctions events:
When 70%–96% of species die
* Often used to mark geologic
timeline boundaries
85
How MANY mass extinctions events have occurred on Earth
5
86
K-Pg mass extinction:
* K stands for Cretaceous.
* Pg stands for Paleogene, the
1st period of Cenozoic Era.
87
A shale layer around the
world contains ______.
iridium
* Iridium no longer naturally occurs in Earth’s crust.
* Iridium is often found in meteorites.
88
Additional shale evidence:
* Microtektites
* Shocked quartz minerals
coesite and stishovite
89
Asteroid’s kinetic energy:
* Proportional to its mass and
the square of its velocity
* Transforms into heat, shock
waves, and air blast
90
Shockwaves move through
_______
air, land, and Earth.
91
Falling ejecta heated air,
sparking wildfires
* Fires produced billions of
tons of soot.
92
Vapor plume contained
chlorine and bromine:
* Destroyed ozone layer
* UV light bathed Earth’s
surface.
93
Read slide 87
readdd
94
NEOs:
* Asteroids, comets, and
meteoroids
* Within 50 million km of
Earth’s orbit
95
Spaceguard Survey Report:
* Commissioned for NASA by
US Congress in 1992
96
NASA’s tasks:
* Find 90% of NEOs >1 km by
2005
* Find 90% of potentially
hazardous objects >140 m
97
Tracking NEOs
Astronomers compare photos of the night sky at different times.
Background stars do not move with respect to each other.
Moving points of light are potential NEOs.
Initial orbital calculations are typically inaccurate.
LOOK AT SLIDE 91
98
Astronomers estimate impact rate by _____.
examining the Moon
99
RECURRANCE INTERVALS METEOR SLIDE
Slide 93
100
Likelihood of a destructive strike is ____.
~0.1%
101
Where do most strikes occur
Most strikes occur in oceans or remote places.
102
The Torino Scale:
* Represents the risk of a collision over the next century
103
NASA’s Asteroid Terrestrial-Impact Last Alert System (ATLAS)
* Robotic telescopes survey sky for small NEO threats.
104
Torintino Scale Slide READ
Slide 96
105
Near-misses are common:
* Some pass within orbits of
satellites.
* One passed beneath orbit of
International Space Station.
106
Impulsive techniques:
* Exploding conventional or
nuclear devices near objects
* Using kinetic impactors to
strike incoming objects
107
Slow-push techniques:
* Mirrors focus sunlight on one
side of an object.
* Mining material from an
object, then ejecting it away
* Useful over decades
108
Impact research determines:
* Crater’s location and size
* Air blast and wind speed
* Air temperature
* Tsunami’s size and locations
109
An impact from an Itokawasized object:
* Crater ~10 km in diameter
* Wind would be 400 km/h,
100 km from impact
* Heat within 100 km would
ignite everything
110
Class Question #5
Why is the element iridium important when researching asteroids and
meteoroid impacts?
a) Since iridium no longer naturally occurs in Earth’s crust, if it is
found in a rock layer it was likely deposited by an asteroid.
b) Iridium is created through shock metamorphism, which most
commonly occurs from an asteroid or meteoroid impact.
c) Most meteoroids are composed mostly of iron, and >90% contain
iridium, an element found in the ionosphere but not in Earth’s crust.
d) Iridium is the preferred coating to use when creating a slow-push
deflection technique that changes an object’s albedo.
(NO GIVEN ANSWER)
