Charles Hakes

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(No Transcript)
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Outline

• Final next Monday (945).
• bring a scantron good eraser, or extra scantron
  sharp pencils
• calculator
• Dark Energy
• Review

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Probable Job Opportunity

• The Academic Success Program regularly funds
  Astronomy Tutors/ Study Group leaders. If you
  might be interested in this for next fall, please
  let me know via email.

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Test Topics (recent/new)

• Chapter 13 - Neutron Stars and Black Holes
• Shwarzschild radius
• Chapter 14 - The Milky way
• Size and Shape
• Spectroscopic parallax
• Cepheid variables
• Mass and dark matter

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Test Topics (recent/new)

• Chapter 15 - Normal and Active Galaxies
• Standard Candles
• Tully-Fisher relationship
• Type I supernova
• Quasars
• Chapter 16 - Hubbles Law and Dark Matter
• Hubbles law
• Distance ladder
• Large scale structure

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Test Topics (recent/new)

• Chapter 17 - Cosmology
• Big Bang
• Age of the universe
• Critical density fate of universe

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Chapter 17

• Cosmology

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Chapter 17Ultra Deep Field - more than 1000
galaxies are in this picture. Total estimate for
the universe - 40,000,000,000.
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Cosmology

• How big is the universe?
• How long has it been here?
• How did it start?
• How long will it last?

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The Fate of the Universe

• Will it keep expanding forever?
• Will gravity cause it to collapse?

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Figure 17.5Escape Velocity

• With enough initial velocity, a spacecraft will
  escape from the Earth
• With insufficient velocity, gravity will bring it
  back to Earth.

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Figure 17.6Model Universes
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The Fate of the Universe

• A high density universe will collapse again into
  a Big Crunch.
• A low density universe will continue to expand
  forever.
• Critical density - boundary between the two
  cases. (9x10-27 kg/m3 5 atoms/m3)
• The ratio of the actual density to the critical
  density is called Wo, the critical density
  parameter.

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The Fate of the Universe

• If you can determine the density of the universe,
  you can determine if there will be a Big Crunch
  or not.

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The Fate of the Universe

• If you can determine the density of the universe,
  you can determine if there will be a Big Crunch
  or not.
• However - most of the matter in the universe is
  dark!

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The Fate of the Universe

• If you can determine the density of the universe,
  you can determine if there will be a Big Crunch
  or not.
• However - most of the matter in the universe is
  dark!
• Even with dark matter estimates, it appears that
  Wo lt 1.0, if that is all you look at...

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The Accelerating Universe
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Figure 17.7Accelerating Universe

• If the universe is slowing down because of
  gravity, distant objects (as seen in the past)
  should be moving faster.
• Recent measurements show this is not the case -
  something is accelerating everything.
• That something is called Dark Energy.
• This dark energy is not understood at all.

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Discovery 17-1The Cosmological Constant
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Figure 17.8Cosmic Age
21

• http//www.newgrounds.com/portal/view/525347

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Current Status of the Universe

• Expanding (and accelerating!) - looks like no big
  crunch for us.
• Composition - looks like Wo1, the critical
  density parameter.
• Normal Matter 4
• Mostly H and He
• Dark Matter 23
• Dark Energy 73

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Big Bang Events

• Inflation - needed to get a uniform density in
  the universe. (lt10-32s!)
• Nucleosynthesis - most of the He (25 of normal
  matter) formed in the first 15 minutes of the
  universe. The rest was left as H.
• Microwave Decoupling (atom formation) - once
  electrons joined the nuclei, then photons were no
  longer scattered and the universe became
  transparent. After a few 10,000s of years.
• Large Scale Structure - normal matter clumps
  around the dark matter.
• Finally acceleration by dark energy.

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The concept that on the grandest of scales, the
universe is similar in appearance everywhere is

• A) general relativity.
• B) special relativity.
• C) homogeneity.
• D) isotropy.
• E) universality.

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The concept that on the grandest of scales, the
universe is similar in appearance everywhere is

• A) general relativity.
• B) special relativity.
• C) homogeneity.
• D) isotropy.
• E) universality.

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• ADT

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How confident were you about your answers on the
Astronomy Diagnostic Test

• A) very confident.
• B) somewhat confident.
• C) not very confident.
• D) just guessing.

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Why is it cold at the North Pole, even during
northern hemisphere summer?

• 1 - Because the pole itself doesnt point very
  close to the direction of the Sun
• 2 - Because there are fewer daylight hours at the
  pole than at lower latitudes (e.g., Durango)
• 3 - Because of the high altitude at the pole
• 4 - Because the pole is further away from the Sun
  than lower latitudes are (e.g., Durango)

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Why is it cold at the North Pole, even during
northern hemisphere summer?

• 1 - Because the pole itself doesnt point very
  close to the direction of the Sun
• 2 - Because there are fewer daylight hours at the
  pole than at lower latitudes (e.g., Durango)
• 3 - Because of the high altitude at the pole
• 4 - Because the pole is further away from the Sun
  than lower latitudes are (e.g., Durango)

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Star A has a parallax shift of 0.4 arc second
Star B has a parallax shift of 0.6 arc seconds

• 1 B is 1.5 times as far away as A
• 2 Star A is at a distance of 4 parsecs (pc)
• 3 Star B is at a distance of 1.66 parsecs (pc)
• 4 Star A is 0.4 times as far away as B

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Star A has a parallax shift of 0.4 arc second
Star B has a parallax shift of 0.6 arc seconds

• 1 B is 1.5 times as far away as A
• 2 Star A is at a distance of 4 parsecs (pc)
• 3 Star B is at a distance of 1.66 parsecs (pc)
• 4 Star A is 0.4 times as far away as B

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Which is correct?

• 1 - The new moon rises at noon.
• 2 - The first quarter moon rises at noon.
• 3 - The full moon rises at noon.
• 4 - The third quarter moon rises at noon.

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Which is correct?

• 1 - The new moon rises at noon.
• 2 - The first quarter moon rises at noon.
• 3 - The full moon rises at noon.
• 4 - The third quarter moon rises at noon.

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In Paris, France (50 degrees north latitude),
what is the longest day of the year?

• 1 March 21
• 2 June 21
• 3 September 21
• 4 December 21

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In Paris, France (50 degrees north latitude),
what is the longest day of the year?

• 1 March 21
• 2 June 21
• 3 September 21
• 4 December 21

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Where along the horizon does the Sun rise on June
21 in Paris, France?

• 1 Due east
• 2 North of east
• 3 South of east
• 4 Cant tell with information given

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Where along the horizon does the Sun rise on June
21 in Paris, France?

• 1 Due east
• 2 North of east
• 3 South of east
• 4 Cant tell with information given

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Where along the horizon does the Sun rise on June
21 in Sydney, Australia?

• 1 Due east
• 2 North of east
• 3 South of east
• 4 Cant tell with information given

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Where along the horizon does the Sun rise on June
21 in Sydney, Australia?

• 1 Due east
• 2 North of east
• 3 South of east
• 4 Cant tell with information given

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On December 21, in Durango, if there is a full
moon, where does it rise?

• 1 Due east
• 2 Almost due east (within 5 degrees)
• 3 South of east (by more than 5 degrees)
• 4 North of east (by more than 5 degrees)

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On December 21, in Durango, if there is a full
moon, where does it rise?

• 1 Due east
• 2 Almost due east (within 5 degrees)
• 3 South of east (by more than 5 degrees)
• 4 North of east (by more than 5 degrees)

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On December 21, in Australia, if there is a full
moon, where does it rise?

• 1 Due east
• 2 Almost due east (within 5 degrees)
• 3 South of east (by more than 5 degrees)
• 4 North of east (by more than 5 degrees)

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On December 21, in Australia, if there is a full
moon, where does it rise?

• 1 Due east
• 2 Almost due east (within 5 degrees)
• 3 South of east (by more than 5 degrees)
• 4 North of east (by more than 5 degrees)

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A 5 meter (diameter) telescope

• 1 gathers 5 times as much light as a 1 m
  telescope
• 2 gathers 1/2 as much light as a 10 m telescope
• 3 gathers 4 times as much light as a 2.5 m
  telescope
• 4 gathers 5/2 as much light as a 2 m telescope

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A 5 meter (diameter) telescope

• 1 gathers 5 times as much light as a 1 m
  telescope
• 2 gathers 1/2 as much light as a 10 m telescope
• 3 gathers 4 times as much light as a 2.5 m
  telescope
• 4 gathers 5/2 as much light as a 2 m telescope

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Which statement about planetary orbits is
incorrect?

• A) All planets orbit the Sun counterclockwise.
• B) Most stay close to the earth's equator in the
  sky.
• C) Most orbits are almost circular, with low
  eccentricities.
• D) All have the Sun at one focus of their
  elliptical orbits.
• E) Most also rotate counterclockwise on their
  axes as well.
•  

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Which statement about planetary orbits is
incorrect?

• A) All planets orbit the Sun counterclockwise.
• B) Most stay close to the earth's equator in the
  sky.
• C) Most orbits are almost circular, with low
  eccentricities.
• D) All have the Sun at one focus of their
  elliptical orbits.
• E) Most also rotate counterclockwise on their
  axes as well.
•  

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Iron meteorites are believed to come from

• A) the core of a differentiated asteroid, now
  broken up.
• B) the crust of a differentiated asteroid, now
  broken up.
• C) a broken up cometary nucleus.
• D) debris from the Kuiper Belt.
• E) interstellar space.
•  

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Iron meteorites are believed to come from

• A) the core of a differentiated asteroid, now
  broken up.
• B) the crust of a differentiated asteroid, now
  broken up.
• C) a broken up cometary nucleus.
• D) debris from the Kuiper Belt.
• E) interstellar space.
•  

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Long-period comets are believed to originally
come from

• A) the asteroid belt.
• B) the Kuiper belt.
• C) the Oort cloud.
• D) the satellite system of Jupiter.
• E) the interstellar medium.
•  

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Long-period comets are believed to originally
come from

• A) the asteroid belt.
• B) the Kuiper belt.
• C) the Oort cloud.
• D) the satellite system of Jupiter.
• E) the interstellar medium.
•  

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The impact of a fragile body in June 1908
produced a huge explosion over

• A) northern Canada.
• B) Alaska.
• C) Siberia.
• D) Mars.
• E) the Moon.
•  

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The impact of a fragile body in June 1908
produced a huge explosion over

• A) northern Canada.
• B) Alaska.
• C) Siberia.
• D) Mars.
• E) the Moon.
•  

54
In what part of the atmosphere does life occur?

• A) exosphere
• B) stratosphere
• C) mesosphere
• D) ionosphere
• E) troposphere
•  
•  

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In what part of the atmosphere does life occur?

• A) exosphere
• B) stratosphere
• C) mesosphere
• D) ionosphere
• E) troposphere
•  
•  

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Which planet shows the widest range of surface
temperatures between day and night?

• A) Mercury
• B) Venus
• C) Earth
• D) Mars
• E) Uranus
•  

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Which planet shows the widest range of surface
temperatures between day and night?

• A) Mercury
• B) Venus
• C) Earth
• D) Mars
• E) Uranus
•  

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Which body has the densest atmosphere?

• A) Mercury
• B) Venus
• C) Earth
• D) Mars
• E) our Moon
•  

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Which body has the densest atmosphere?

• A) Mercury
• B) Venus
• C) Earth
• D) Mars
• E) our Moon
•  

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Which of these gets brightest so bright as to be
seen during daylight at times?

• A) Mercury
• B) Venus
• C) Mars
• D) Jupiter
• E) Saturn
•  

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Which of these gets brightest so bright as to be
seen during daylight at times?

• A) Mercury
• B) Venus
• C) Mars
• D) Jupiter
• E) Saturn
•  

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Assume a planet orbits exactly three times as far
from the Sun as the Earth.

• 1 - Its period is 3 years exactly.
• 2 - Its period is between 3 and 5 years
• 3 - Its period is between 5 and 7 years
• 4 - Its period is 7 years or more.

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Assume a planet orbits exactly three times as far
from the Sun as the Earth.

• 1 - Its period is 3 years exactly.
• 2 - Its period is between 3 and 5 years
• 3 - Its period is between 5 and 7 years
• 4 - Its period is 7 years or more.

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Two planets have orbits with the same sized
semi-major axis. Which is true?

• 1 - The planet with the most eccentric orbit
  moves faster all the time.
• 2 - The planet with the most eccentric orbit
  moves faster some of the time.
• 3 - The planet with the most eccentric orbit
  never moves faster.
• 4 - Not enough information to answer.

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Two planets have orbits with the same sized
semi-major axis. Which is true?

• 1 - The planet with the most eccentric orbit
  moves faster all the time.
• 2 - The planet with the most eccentric orbit
  moves faster some of the time.
• 3 - The planet with the most eccentric orbit
  never moves faster.
• 4 - Not enough information to answer.

66
A fast moving freight train hits a car. The car
is destroyed and the train isnt, so

• 1 - the magnitude of the force of the train on
  the car is greater than the magnitude of the
  force of the car on the train
• 2 - the magnitude of the force of the train on
  the car is smaller than the magnitude of the
  force of the car on the train
• 3 - the magnitude of the force of the train on
  the car is equal to the magnitude of the force of
  the car on the train
• 4 - none of the preceding

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A fast moving freight train hits a car. The car
is destroyed and the train isnt, so

• 1 - the magnitude of the force of the train on
  the car is greater than the magnitude of the
  force of the car on the train
• 2 - the magnitude of the force of the train on
  the car is smaller than the magnitude of the
  force of the car on the train
• 3 - the magnitude of the force of the train on
  the car is equal to the magnitude of the force of
  the car on the train
• 4 - none of the preceding

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Which has the most kinetic energy?

• 1 A 1 kg Mass with velocity 4 m/s.
• 2 A 2 kg Mass with velocity 3 m/s.
• 3 A 3 kg Mass with velocity 2 m/s.
• 4 A 4 kg Mass with velocity 1 m/s.

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Which has the most kinetic energy?

• 1 A 1 kg Mass with velocity 4 m/s.
• 2 A 2 kg Mass with velocity 3 m/s.
• 3 A 3 kg Mass with velocity 2 m/s.
• 4 A 4 kg Mass with velocity 1 m/s.

70
Which mass pair has the greatest gravitational
force between them?

• 1 A 5Msolar mass and a 4Msolar mass separated by
  4 AU.
• 1 A 4Msolar mass and a 3Msolar mass separated by
  3 AU.
• 1 A 3Msolar mass and a 2Msolar mass separated by
  2 AU.
• 1 A 2Msolar mass and a 1Msolar mass separated by
  1 AU.

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Which mass pair has the greatest gravitational
force between them?

• 1 A 5Msolar mass and a 4Msolar mass separated by
  4 AU.
• 1 A 4Msolar mass and a 3Msolar mass separated by
  3 AU.
• 1 A 3Msolar mass and a 2Msolar mass separated by
  2 AU.
• 1 A 2Msolar mass and a 1Msolar mass separated by
  1 AU.

72
Two planets have orbits with the same periods.
Which is true?

• 1 - Their velocities must be the same.
• 2 - They must have the same eccentricity.
• 3 - They must have the same semi-major axis.
• 4 - They must collide with each other.

73
Two planets have orbits with the same periods.
Which is true?

• 1 - Their velocities must be the same.
• 2 - They must have the same eccentricity.
• 3 - They must have the same semi-major axis.
• 4 - They must collide with each other.

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Temperature

• Which feels hotter?
• 1 300 F 2 300 C 3 300 K

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Temperature

• Which feels hotter?
• 1 300 F 2 300 C 3 300 K
• (Fahrenheit ) (Celsius) (Kelvin)

76
Assume that the Sun rises at 600 A.M. What time
does the third quarter Moon rise?

• 1 900 A.M.
• 2 1200 noon
• 3 900 P.M.
• 4 1200 midnight

77
Assume that the Sun rises at 600 A.M. What time
does the third quarter Moon rise?

• 1 900 A.M.
• 2 1200 noon
• 3 900 P.M.
• 4 1200 midnight

78
You are in Paris, France (50 degrees north
latitude), on June 21.

• What is the highest angle above the horizon that
  the Sun achieves?
• 1 16.5 above the Southern horizon
• 2 26.5 above the Southern horizon
• 3 63.5 above the Southern horizon
• 4 73.5 above the Southern horizon

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You are in Paris, France (50 degrees north
latitude), on June 21.

• What is the highest angle above the horizon that
  the Sun achieves?
• 1 16.5 above the Southern horizon
• 2 26.5 above the Southern horizon
• 3 63.5 above the Southern horizon
• 4 73.5 above the Southern horizon

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Observing from a latitude of 25 North

• 1 - The star Polaris appears about 65 above the
  horizon.
• 2 - The celestial equator has a maximum height of
  65 above the horizon.
• 3 - The star Polaris appears about 25 north of
  the zenith point.
• 4 - The celestial equator has a maximum height of
  25 above the horizon.

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Observing from a latitude of 25 North

• 1 - The star Polaris appears about 65 above the
  horizon.
• 2 - The celestial equator has a maximum height of
  65 above the horizon.
• 3 - The star Polaris appears about 25 north of
  the zenith point.
• 4 - The celestial equator has a maximum height of
  25 above the horizon.

82
The universe became transparent to radiation
during

1. Nucleosynthesis
2. Decoupling
3. Structure Formation
4. Cosmic Acceleration

83
According to standard Big Bang theory, if
Ho50km/s/Mpc, the maximum universe age is

1. 12 billion years
2. 14 billion years
3. 17 billion years
4. 20 billion years