Exam 3 Review

Outline

1. Exam logistics

2. Quiz 13 Discussion

3. Exam Review

Outline For Rest of Semester• 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.

• 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.

Third Exam

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 activity2. If they did, they would be expected to have less greenhouse gasses3. If they did, they would have a magnetic field that is aligned with their spin axis4. If they did, they would be expected to have more greenhouse gasses5. 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 activity2. If they did, they would be expected to have less greenhouse gasses3. If they did, they would have a magnetic field that is aligned with their spin axis4. If they did, they would be expected to have more greenhouse gasses5. 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)

Greenhouse gasses absorb energy that would have been otherwise sent back to space.

Visible light passes through with ease

Reflected energy has different wavelength

Heat from wire

Heat from bulb

Radiation from bulb

Solar panel

Solar radiation

Radiation energy in must equal heat energy + radiation energy out if temp. inside dotted line is not changing

Heat from wire

Heat from bulb

Radiation from bulb

Solar panel

Solar radiation

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

BBCannon Ball

Water

Oven

• 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

http://hyperphysics.phy-astr.gsu.edu/HBASE/quantum/atspect.html

Nitrogen Gas tube Light from tube after being passed through prism

Ene

rgy

Flu

x

1

2

3

4

5

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!

Venus’s orbital period is 224 daysVenus’s rotation period is 243 days (retrograde)

B

C

D

Draw ball and arrow at A, B, C, D

How long is Venus’s day?

R

Takes about 60 days to get to A (224/4 = 60)

In 60 days it rotates 60/243 = (about) 0.25 of a turn.

Jupiter and Saturn

Which planet will appear more often at opposition, Saturn or Neptune?

1. Saturn2. Same3. 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.