Transcript Lecture 13 (Exam 3 Review)

Exam 3 Review
Outline
1. Exam logistics
2. Quiz 13 Discussion
3. Exam Review
Outline For Rest of Semester
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Oct. 29th Chapter 9 (Earth)
Nov 3rd and 5th Chapter 9 and Chapter 10 (Earth and Moon)
Nov. 10th and 12th Mars, Venus, and Mercury
Nov. 17th and 19th Jupiter and Saturn
Nov 24th Uranus and Neptune
Nov 26th Thanksgiving
Dec. 1st - Exam 3
Dec. 3rd – Pluto, and the Kuiper Belt
Dec. 8th and 10th – Chapter 7 and 8 (Comparative Planetology
I and II)
• Tuesday December 15th (7:30 am – 10:15 am) Final Exam
Final same format as other exams (on Blackboard in Testing Center).
You may take the exam on Tuesday or Wednesday. Times TBD.
Third Exam
• You may take on either Tuesday and
Wednesday
– Tuesday: 9am – 7:30pm
– Wednesday: 9am and 6pm
• 50 questions.
• In the Testing and Tutoring Center in Sub II
(Student Union Building II)
• Exam will be administered via Blackboard
system.
Study Suggestions
1. Re-take the quizzes. Don’t try to memorize,
but make sure that you understand the concept
and connect it to other questions and topics
covered. Compare your notes about this with a
peer.
2. Re-do 1. for the lecture problems.
3. Look at questions in textbook. If any of them
look like questions I have asked on a quiz, try
to answer the question.
4. Look at quiz question on textbook web page. If
any of them look like questions I have asked on
a quiz, try to answer the question.
Example of identifying the concept
• You see a question that asks why type of
energy transfer is important for a given
situation.
• After answering the question, ask:
– What are the other modes of energy transfer?
– What are at least two examples of the two
other modes of energy transfer?
– How do these modes apply to astronomy?
Outline
1. Exam logistics
2. Quiz 13 Discussion
3. Exam Review
• Why do we think Uranus and Neptune did not form at
their present distance from the Sun?
1. If they did, they would be expected to have more
geologic activity
2. If they did, they would be expected to have less
greenhouse gasses
3. If they did, they would have a magnetic field that is
aligned with their spin axis
4. If they did, they would be expected to have more
greenhouse gasses
5. If they did, they would be expected to have interiors
more like Saturn
• Why do we think Uranus and Neptune did not form at
their present distance from the Sun?
1. If they did, they would be expected to have more
geologic activity
2. If they did, they would be expected to have less
greenhouse gasses
3. If they did, they would have a magnetic field that is
aligned with their spin axis
4. If they did, they would be expected to have more
greenhouse gasses
5. If they did, they would be expected to have interiors
more like Saturn
Exaggerated Seasons On Uranus
• Uranus’s axis of rotation lies
nearly in the plane of its
orbit, producing greatly
exaggerated seasonal
changes on the planet
• This unusual orientation may
be the result of a collision
with a planetlike object early
in the history of our solar
system. Such a collision
could have knocked Uranus
on its side
• How long is a day on Uranus?
• How long is a day on Uranus?
• To answer, suppose the spin axis pointed
directly at the sun. In one rotation (about
17 hours), what does a person on the
equator see?
• (I won’t ask you this, but it often comes up)
Outline
1. Exam logistics
2. Quiz 13 Discussion
3. Exam Review
Earth
The Greenhouse effect
• Two usages:
– An effect that occurs on a
planet with an Earth-like
atmosphere
– An enhancement of the above
effect due to human activity
The greenhouse effect simplified
Visible light passes
through with ease
Greenhouse
gasses (e.g., CO2)
Reflected energy has
different wavelength
Greenhouse gasses absorb energy that
would have been otherwise sent back to
space.
Visible light passes through with
ease
Solar radiation
Heat
from
wire
Solar panel
Heat from
bulb
Radiation
from bulb
Radiation energy in must equal heat energy + radiation
energy out if temp. inside dotted line is not changing
Solar radiation
Heat
from
wire
Solar panel
Heat from
bulb
Radiation
from bulb
Energy Transfer
• Three modes of energy transfer
–Convective – Bulk movement of
mass
–Conductive – jiggling material
(atoms and molecules) but no bulk
movement of mass
–Radiative – Electromagnetic
Energy Transfer
• How are the modes of energy transfer
operating here?
– Convective
– Conductive
– Radiative
Radiation Energy in =
Radiation Energy out
http://stephenschneider.stanford.edu/Graphics/EarthsEnergyBalance.png
If the amount of CO2 in Earth's
atmosphere doubled, what would happen
to the number labeled “A”?
• How much energy does the Earth get from
the sun from convection and conduction?
• How much energy does the sun get from
convection and conduction?
About zero
Cannon Ball
BB
Oven
Water
• Which cools off first?
• What modes of energy transfer are
present when they are in the air?
• What modes of energy transfer are
present when they are in the water?
• If you measure the temperature of the BB
and the cannonball when they are in the
water, and the cannonball is hotter, what
can you conclude about how long the
objects have been there?
Aurora
(northern and southern lights)
Aurora
• Certain solar wind
conditions energize
electrons and ions in
magnetosphere.
Some collide with
atoms in Earth’s
atmosphere.
• Collisions of charged
particles atoms in
atmosphere create
aurora
Nitrogen Gas tube
Light from tube after being
passed through prism
http://hyperphysics.phy-astr.gsu.edu/HBASE/quantum/atspect.html
Energy Flux
5
4
3
2
1
0
Mercury and Venus
The reason the temperature on the dark side of
Mercury is warmer than originally expected is
that
1. winds in Mercury's tenuous atmosphere carry
heat from the daytime side to the night side.
2. several very active volcanoes on Mercury,
produced by tidal stresses from the Sun,
produce excess heat.
3. Mercury does not rotate synchronously with
its orbital period.
4. Mercury's large iron core conducts heat
through the planet.
At position D, an observer on the equator of the
blue planet is pointing towards the sun when he
points along his zenith (as indicated by the black
arrow). The blue planet rotates around its axis
and around its sun in a counterclockwise
direction.
About what time will
it be for
the observer when he
is next at position D?
Draw it!
At position D, an observer on the equator of the blue
planet is pointing towards the sun when he points along
his zenith (as indicated by the arrow). The planet rotates
around its sun in a counterclockwise direction. The
planet rotates around its axis in a clockwise direction
(retrograde).
What time will it be
for the observer when
he is at position B?
Draw it!
The length of one solar day on the planet
in the previous question is
1. equal to one-quarter of that planet's
orbital period.
2. one hour.
3. equal to that planet's orbital period.
4. one-half of that planet's orbital period.
Draw it!
How long is Venus’s day?
Draw ball and arrow
at A, B, C, D
C
D
B
Takes about 60 days
to get to A (224/4 = 60)
Venus’s orbital period is 224 days
Venus’s rotation period is 243 days
(retrograde)
In 60 days it rotates
60/243 = (about) 0.25
of a turn.
R
Jupiter and Saturn
Which planet will appear more often at
opposition, Saturn or Neptune?
1. Saturn
2. Same
3. Neptune
Saturn is less massive than Jupiter but has
almost the same size. Why is this?
1. Saturn's interior is hotter than that of Jupiter.
2. Saturn is rotating faster than Jupiter, and the
increased centrifugal force results in a larger
size.
3. The small mass of Saturn exerts less
gravitational force and is unable to compress the
mass as much as in Jupiter.
4. Saturn is composed of lighter material than
Jupiter.
Saturn is less massive than Jupiter but has
almost the same size. Why is this?
1. Saturn's interior is hotter than that of Jupiter.
2. Saturn is rotating faster than Jupiter, and the
increased centrifugal force results in a larger
size.
3. The small mass of Saturn exerts less
gravitational force and is unable to compress the
atmospheric mass as much as in Jupiter.
4. Saturn is composed of lighter material than
Jupiter.
Some of the small shepherd satellites within Saturn's
ring system are also inside Saturn's Roche Limit. Why
are they not torn apart by tidal forces due to Saturn's
gravity?
1. The interaction between Saturn's strong magnetic
field and the magnetic fields generated by the shepherd
satellites helps to hold the satellites together.
2. Unlike the ring particles, the satellites are large
enough to produce significant gravitational fields of their
own, and these counteract the tidal forces.
3. The Roche Limit applies only to the ring particles, not
to anything as large as a satellite
4. The Roche Limit only applies to objects held together
by mutual gravitational attraction, not to chunks of rock
like the shepherd satellites.
Some of the small shepherd satellites within Saturn's
ring system are also inside Saturn's Roche Limit. Why
are they not torn apart by tidal forces due to Saturn's
gravity?
1. The interaction between Saturn's strong magnetic
field and the magnetic fields generated by the shepherd
satellites helps to hold the satellites together.
2. Unlike the ring particles, the satellites are large
enough to produce significant gravitational fields of their
own, and these counteract the tidal forces.
3. The Roche Limit applies only to the ring particles, not
to anything as large as a satellite
4. The Roche Limit only applies to objects held together
by mutual gravitational attraction, not to chunks of rock
like the shepherd satellites.