Final Cosmos

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8/13/2019 Final Cosmos http://slidepdf.com/reader/full/final-cosmos 1/52  Question 1 3 out of 3 points The most important factor in determining a stars eventual fate is its: Answer Selected Answer: mass Correct Answer: mass Response Feedback: Correct, its mass is tied to the luminosity (since the star is in hydrostatic equilibrium) and thus to the lifetime of the star.  Question 2 1 out of 1 points In 5 billion years the Sun will become a black hole: Answer Selected Answer: False Correct Answer: False Response Feedback: Correct, remember lower mass stars like the Sun eventually become white dwarfs  Question 3 0 out of 3 points When an atom absorbs a high energy photon and an electron is ejected we call this: Answer Selected Answer: emission Correct Answer: ionization Response Feedback: Incorrect, ionization is removing an electron from an atom (creating an ion)  Question 4 0 out of 3 points A red giant star like Arcturus must have a: Answer Selected Answer: mass much greater than the Sun Correct Answer: luminosity much larger than the Sun Response Feedback: Incorrect, remember the Sun will eventually expand and cool to become a red giant (and thus the other 3 answers must be wrong)  Question 5 3 out of 3 points

Transcript of Final Cosmos

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  Question 13 out of 3 points

The most important factor in determining a stars eventual fate is its:Answer

Selected Answer:

massCorrect Answer:

mass

Response

Feedback:Correct, its mass is tied to the luminosity (since the star is in hydrostatic

equilibrium) and thus to the lifetime of the star.

  Question 21 out of 1 points

In 5 billion years the Sun will become a black hole:Answer

Selected Answer: False

Correct Answer: False

Response

Feedback:Correct, remember lower mass stars like the Sun eventually becomewhite dwarfs

  Question 30 out of 3 points

When an atom absorbs a high energy photon and an electron is ejected we call this:Answer

Selected Answer:

emission

Correct Answer:ionization

Response

Feedback:Incorrect, ionization is removing an electron from an atom (creating

an ion)

  Question 40 out of 3 points

A red giant star like Arcturus must have a:Answer

Selected Answer:

mass much greater than the Sun

Correct Answer:

luminosity much larger than the Sun

Response

Feedback:Incorrect, remember the Sun will eventually expand and cool to become a

red giant (and thus the other 3 answers must be wrong)

  Question 53 out of 3 points

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Tonight you observe the planet Saturn at midnight high in the Southern skies, you knowthat:Answer

Selected Answer:

Saturn and Earth must be on the same side of the Sun

Correct Answer:

Saturn and Earth must be on the same side of the Sun

Response Feedback: Correct, Saturn must be opposite the Sun at this point.

  Question 63 out of 3 points

This is an image of:

Answer

Selected Answer:

a globular cluster

Correct Answer:

a globular cluster

Response Feedback: Correct

  Question 73 out of 3 points

Uranus is peculiar because its:Answer

Selected Answer:

axis of rotation is so highly tilted

Correct Answer:

axis of rotation is so highly tilted

Response

Feedback:Correct, Uranus is tilted 98 degrees to its orbit and thus moves around theSun on its "side", but not the part of Uranus pointed at the Sun is not

always the same.

  Question 83 out of 3 points

As seen from Earth, Jupiter cannot:

Answer

Selected Answer:

eclipse the Sun

Correct Answer:

eclipse the Sun

Response Feedback: Correct, Jupiter cannot come between the Earth and the Sun

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  Question 93 out of 3 points

Greenhouse gases warm a planet like Earth by:Answer

Selected Answer:

retaining more infrared light emitted by the EarthCorrect Answer:

retaining more infrared light emitted by the Earth

Response

Feedback:Correct, the radiation emitted by the Earth is at longer (infrared)

wavelengths compared to the Sun (optical), it is the retention of this

radiation that heats the Earth.

  Question 103 out of 3 points

The Milky Way is:Answer

Selected Answer:

the name of our Galaxy

Correct Answer:

the name of our Galaxy

Response Feedback: Correct, from ancient Greek myths

  Question 113 out of 3 points

About what temperature did the cosmic microwave background have at the time of its

formation?

Answer

Selected Answer:

3,000 K

Correct Answer:

3,000 K

Response

Feedback:Correct, when it formed the Universe had cooled to roughly 3,000 K, the

temperature of the surface of a star.

  Question 123 out of 3 points

How does the observed density in stars compare with the critical density?Answer

Selected Answer:

it is much less

Correct Answer:

it is much less

Response Correct, the density of material in stars averaged over the enormous volume

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Feedback: of space is much less than the density that required to close the Universe

(make it re-collapse), although the density of individual stars is much larger

than the critical density

  Question 130 out of 1 points

Planetary nebulae are the sites of new planet formation:Answer

Selected Answer: True

Correct Answer: False

Response

Feedback:Incorrect, planetary nebulae are the end stages of the lives of stars like the

Sun. Early astronomers mistook them for forming stars.

  Question 143 out of 3 points

The Jovian planets retained most of their atmospheres because:Answer

Selected Answer:

they were very cold when formed

Correct Answer:

they were very cold when formed

Response

Feedback:Correct, remember the atmosphere retention simulations from the lasthomework at:

http://www.physics.louisville.edu/~jtl/Phys107-

2008B/atmo_retention.html

  Question 153 out of 3 points

Jupiter's composition is closest to that of:Answer

Selected Answer:

the Sun

Correct Answer:

the Sun

Response Feedback: Correct, both the Sun and Jupiter are mostly H and He

  Question 163 out of 3 points

A Full Moon is at position:

Answer

Selected Answer:

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e

Correct Answer:

e

Response

Feedback:

Correct, a full Moon is when the Moon is on the opposite side of the

Earth from the Sun

  Question 170 out of 1 points

Jupiter has only 5 moons:Answer

Selected Answer: True

Correct Answer: False

Response Feedback: Incorrect, it has more than 4 dozen Moons

  Question 181 out of 1 points

The majority of the mass of the Milky Way is in the form of dark matter:Answer

Selected Answer: True

Correct Answer: True

Response

Feedback:Correct, the best evidence is the velocities of stars and gas clouds in

the outer disk.

  Question 190 out of 3 points

An OB star like Rigel moving through the galactic disk is a:Answer

Selected Answer:

Population II star

Correct Answer:

Population I star

Response

Feedback:Incorrect, the name given to the stars of the Galactic disk is Population I,the older stars of the halo are Pop II, and the first generation of stars

(which we have not yet discovered and may have all "died") are Pop III.

  Question 203 out of 3 points

What component of the primordial interstellar cloud became the inner planets?Answer

Selected Answer:

The dust grains

Correct Answer:

The dust grains

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Response

Feedback:The inner planets were made from the dust grains in the early Solar

nebula which had clumped together to form planetesimals.

  Question 213 out of 3 points

What is the largest object in the Solar System?Answer

Selected Answer:

the Sun

Correct Answer:

the Sun

Response

Feedback: Neither globular clusters or supermassive black holes are in our Solar

system (they are in the Milky Way galaxy), and by thus by default it is the

Sun.

  Question 22

3 out of 3 points

Using the soon to be launched Kepler satellite astronomers detect a planet with a semi-

major axis of 1 AU around a G2V star in Cygnus, its period will be:Answer

Selected Answer:

1 year

Correct Answer:

1 year

Response

Feedback:Right, a G2V star is like the Sun and the planet with a 1 AU orbit is the

Earth which has an orbital period of 1 year

  Question 233 out of 3 points

You observe a Cephied variable in a distant galaxy, you can now determine the galaxies:Answer

Selected Answer:

distance

Correct Answer:

distance

Response Feedback: Correct, since Cephieds are standard candles

  Question 243 out of 3 points

The cosmic microwave background shows that the Universe evolved from a:Answer

Selected Answer:

hot dense state

Correct Answer:

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hot dense state

Response

Feedback:Correct, the Hubble expansion shows that the Universe was once much

smaller while the cosmic microwave background must have been made ofmuch higher energy photons before they were redshifted by the expansion

of the Universe.  Question 25

1 out of 1 points

Jupiter has moons larger than the planet Mercury:Answer

Selected Answer: True

Correct Answer: True

Response

Feedback:Correct, Ganymede is larger and Callisto is is the same size as

Mercury

  Question 26

0 out of 1 pointsPolaris (the "North Star") is a circumpolar star to all observers on the Earth:Answer

Selected Answer: True

Correct Answer: False

Response Feedback: Incorrect, Polaris is not visible from the Southern hemisphere.

  Question 271 out of 1 points

All globular clusters have the same luminosity:Answer

Selected Answer: FalseCorrect Answer: False

Response Feedback: Correct, they vary between 100,000 and 1,000,000 stars.

  Question 283 out of 3 points

Which of the following has a linear size or radius closest to the radius of a white dwarf?Answer

Selected Answer:

the Earth

Correct Answer:

the Earth

Response

Feedback:Correct, a white dwarf is roughly the mass of the Sun squeezed into the

size of the Earth

  Question 293 out of 3 points

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Why is the cosmic microwave background temperature so cool now?Answer

Selected Answer:

The expansion of the Universe has cooled it

Correct Answer:

The expansion of the Universe has cooled it

Response

Feedback:The radiation has been redshifted (the wavelength of the radiation has been

stretched) and thus it is at lower energies - so the cosmic background

corresponds to a lower temperature blackbody.

  Question 303 out of 3 points

The best evidence that man never landed on the Moon is:Answer

Selected Answer:

none of the above - man landed on the Moon

Correct Answer:

none of the above - man landed on the Moon

Response Feedback: Correct, remember:

"If You Open Your Mind Too Much Your Brain Will Fall Out"  

  Question 313 out of 3 points

When we look at the great galaxy in Andromeda we see it as it was approximately:Answer

Selected Answer:

2.5 million years ago

Correct Answer:

2.5 million years ago

Response

Feedback:Correct, the Andromeda galaxy (the nearest large galaxy to our own Milky

Way) is about 2.5 million light years away, and thus it takes light 2.5

million years to reach us.

  Question 32

3 out of 3 points

Clusters of galaxies are bound together by:Answer

Selected Answer:

gravity

Correct Answer:

gravity

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Response

Feedback:Correct, the attractive force of gravity binds together astronomical objects

from planets and stars to galaxies and clusters of galaxies

  Question 333 out of 3 points

The reason astronomers use near-infrared observations is to:Answer

Selected Answer:

 penetrate interstellar dust clouds

Correct Answer:

 penetrate interstellar dust clouds

Response

Feedback:Correct, one of the key advantages of near-infrared is its ability to

 penetrate dust clouds where shorter wavelength opitcal light is absorbed

  Question 343 out of 3 points

Particle physicists are interested in the conditions in the early Universe because:Answer

Selected

Answer: this allows them to test unified field theories uniting the fundamental

forces of nature

Correct

Answer: this allows them to test unified field theories uniting the fundamental

forces of nature

Response

Feedback:Correct, the densities and energies in the early Universe cannot yet (and

may never) be replicated in particle accelerators

  Question 353 out of 3 points

We can measure the mass of the black hole at the center of the Milky Way galaxy by:Answer

Selected Answer:

watching the orbits of stars in the center and using Kepler's Third Law

Correct Answer:

watching the orbits of stars in the center and using Kepler's Third Law

Response

Feedback:Correct, remember the following animation from class (image from the

UCLA Galactic Center group - This animation was created by Prof. AndreaGhez and her research team at UCLA and are from data sets obtained with

the W. M. Keck Telescopes." Image creators include Andrea Ghez, AngelleTanner, Seth Hornstein, and Jessica Lu).

  Question 36

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3 out of 3 points

Consider a comet which was recently discovered near the orbit of Jupiter at a distance of

5 AU from the Sun, if astronomers find that it is in an elliptical orbit around the Sun and

 passes within 1 AU of the Sun, then which of the following statements must be true:Answer

Selected Answer:the semi-major axis of its orbit must be at least 3 AU

Correct Answer:

the semi-major axis of its orbit must be at least 3 AU

Response

Feedback:Correct, this comet must travel at least 6 AU from side to side of its orbit

(1 AU on one side and 5 AU on the other), so its semi-major axis (half the

long axis of the ellipse) must be 3 AU.

 Note that period of 1 year = 1 AU and period of 11 years ~ 5 AU by

Kepler's Third Law (P2=a3)

  Question 373 out of 3 points

How do we know how old the Solar System is?Answer

Selected

Answer: By measuring the products of radioactive decay in old rocks andmeteors

Correct Answer:

By measuring the products of radioactive decay in old rocks and

meteors

Response

Feedback:Correct, this is known as radiometric dating and uses many elements not just the well-

known carbon-14 method used to date relatively recent organic materials (such as

achaeological remains). 

  Question 383 out of 3 points

Why are objects like Mercury and the moons of Earth, Jupiter and Saturn so heavily

cratered?Answer

Selected

Answer: Intense bombardment by asteroids and planetesimals subsequent to their

 birthCorrect Answer:

Intense bombardment by asteroids and planetesimals subsequent to their

 birth

Response

Feedback:Correct, the impact of small bodies leads to cratering and withouttectonic activity, melting of ice or weathering the craters remain

  Question 39

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3 out of 3 points

A moon must be:Answer

Selected Answer:

orbiting a planet

Correct Answer:

orbiting a planet

Response Feedback: Correct, by definition.

  Question 403 out of 3 points

The interstellar medium of galaxies today show more "metals" than that seen in distant

galaxies because:Answer

Selected

Answer: more supernovae have gone off to enrich the gasover the past few billion

years

Correct Answer:

more supernovae have gone off to enrich the gasover the past few billionyears

Response

Feedback:Correct, remember two things:1) when we look at distant galaxies we are seeing them as they were in

the past

2) the Universe started out with H and He and no heavier elements like

C, N, O, Si, Fe

  Question 413 out of 3 points

Dark energy is:Answer

Selected

Answer: inferred to exist because distant supernovae are fainter than the otherwise

should be due to the expansion of the Universe

Correct

Answer: inferred to exist because distant supernovae are fainter than the otherwise

should be due to the expansion of the Universe

ResponseFeedback:

Correct, dark energy is what astronomers call the energy that is causing theexpansion of the Universe to accelerate, which results in distant supernovae

 being even further from the Sun than they would be given due to the

expansion of the Universe.

  Question 421 out of 1 points

The Sun has a lifetime much longer than a B-type star like Regulus:Answer

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Selected Answer: True

Correct Answer: True

Response

Feedback:Correct, remember massive stars are much more luminous than the Sun

and so use up their fuel very quickly ("live fast and die young")

 Question 43 3 out of 3 points

The surface of Venus is mostly low density rock, while the average density is similar to

that of Earth, the interior of Venus must therefor be:Answer

Selected Answer:

iron like the Earth

Correct Answer:

iron like the Earth

Response Feedback: Correct, like the Earth Venus must have an iron core

  Question 440 out of 3 points

Which diagram shows the emission of the lowest energy photon?

Answer

Selected Answer:

C

Correct Answer:

A

Response

Feedback:Incorrect, emission is when an electron goes from an outer (higher energy)

orbital to an inner (lower energy) orbital giving off energy in the form of a

 photon, the smaller the jump the less energy released.

  Question 450 out of 3 points

Tonight you go outside and see a star at the position marked (labeled as "position at6pm"), at noon you would expect to see the star at the position labeled:

Answer

Selected Answer:

 b

Correct Answer:

c

Response

Feedback:Incorrect, this is a circumpolar star and takes 24 hours to circle the pole -

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for the direction of motion remember it will "rise" in the East.

Look at the web simulation:

http://astro.unl.edu/naap/motion2/animations/ce_hc.swf

  Question 460 out of 3 points

The moons of Mars were likely formed:Answer

Selected Answer:

as a result of the impact of a large body on Mars

Correct Answer:

in the asteroid belt before their later capture

Response Feedback: Incorrect, these irrgularly shaped objects are likely captured asteroids

  Question 470 out of 1 points

The Universe appears homogeneous and isotropic to our eyes:

Answer

Selected Answer: True

Correct Answer: False

Response

Feedback:Incorrect, it is only when you average over large volumes that the

Universe is shown to be homogeneous and isotropic.

  Question 48

3 out of 3 pointsThe greenhouse effect on Earth is currently:Answer

Selected

Answer: a largely natural process keeping the Earth at a temperature abovefreezing

Correct Answer:

a largely natural process keeping the Earth at a temperature abovefreezing

Response

Feedback:

Correct, the greenhouse effect is important in keeping the Earth

habitable, but could potentially be dangerous to human civilization

  Question 493 out of 3 points

Dark matter is composed of:Answer

Selected Answer:

no one knows for sure

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Correct Answer:

no one knows for sure

Response Feedback: Correct, this is one of the current unsolved mysteries in astronomy

  Question 50

0 out of 3 pointsObservations of young stars show features like this because:

Answer

Selected Answer:

a and b

Correct Answer:

 b and c

Response

Feedback: Incorrect, the collapse of the cloud to form the star results in somematerial falling into a disk due to rotation, and it is out of this material that

new planets form.

  Question 513 out of 3 points

Which of the following is the best evidence for the existence of dark matter in the Milky

Way:Answer

Selected Answer:

the orbital speeds of gas clouds outside the orbit of the Sun

Correct Answer:

the orbital speeds of gas clouds outside the orbit of the Sun

Response

Feedback:Correct, see Figure 9-9 and the discussion beginning on page 181 in

the text.

  Question 523 out of 3 points

The Hubble Space Telescope has taken the clearest views of the distant Universe

 because:Answer

Selected

Answer:

it is above the atmosphere and thus above the blurring caused byatmospheric motions

Correct

Answer: it is above the atmosphere and thus above the blurring caused byatmospheric motions

Response Feedback: Correct, the motions in the Earth's atmosphere "smear" out images

  Question 53

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1 out of 1 points

Pulsars are rotating white dwarfs:Answer

Selected Answer: False

Correct Answer: False

Response Feedback: Correct, pulsars are rotating neutron stars.

  Question 541 out of 1 points

Jupiter's moon Io has volcanoes:Answer

Selected Answer: True

Correct Answer: True

Response Feedback: Correct

  Question 553 out of 3 points

Jupiter contains approximately what fraction of the mass of the planets:Answer

Selected Answer:

70%

Correct Answer:

70%

Response

Feedback:Correct, Jupiter contains most of the mass in the planets, although

remember it is a small fraction of the Sun

  Question 56

3 out of 3 points

If we look at a galaxy 4.5 billion light years away we see it as it was:Answer

Selected Answer:

when the Earth formed

Correct Answer:

when the Earth formed

Response Feedback: Correct, remember the Earth formed roughly 4.5 billion years ago

  Question 573 out of 3 points

Incandescent light bulbs have a temperature of ~2700 K, this means that their light is

emitted mostly:Answer

Selected Answer:

at infrared wavelengths

Correct Answer:

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at infrared wavelengths

Response

Feedback:Correct, the cooler temperature (relative to the Sun) means that these bulbs

emit most of their light at longer - infrared - wavelengths. This is whythey are so inefficient.

  Question 581 out of 1 points

A closed Universe is one that re-collapses at some point in its history:Answer

Selected Answer: True

Correct Answer: True

Response Feedback: Correct, this is the definition of a closed Universe.

  Question 593 out of 3 points

You have two blackbodies of the same size but differing luminosity, what statement

must be true?Answer

Selected Answer:

the more luminous one is hotter

Correct Answer:

the more luminous one is hotter

Response

Feedback:Correct, remember the luminosity goes as temperature to the fourth powertimes the radius squared for a blackbody, and the the more luminous

object must be hotter.

  Question 601 out of 1 points

Ceres is a dwarf planet:Answer

Selected Answer: True

Correct Answer: True

Response

Feedback:Correct, remember that while Ceres is large enough to be pulled by self-

gravity into a "round" shape it is in the asteroid belt and thus has notcleared its orbit of similarly size bodies.

  Question 610 out of 1 points

The temperature of the cosmic microwave background (CMB) varies widely (by a factor

of 10 or more) across the sky:Answer

Selected Answer: True

Correct Answer: False

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Response

Feedback:Incorrect, the temperature varies by only a small fraction (about 1 part

in 100,000) 

  Question 621 out of 1 points

The average density of "normal" matter like atoms and neutrinos is much less than thecritical density required to close the Universe:Answer

Selected Answer: True

Correct Answer: True

Response

Feedback:Correct, "normal" matter is a small fraction of what makes up the

Universe both dark matter and dark energy are much larger fractions of

the Universe.

  Question 631 out of 1 points

What do astronomers infer from the motion of the distant galaxies?Answer

Selected Answer:

The Universe is expanding.

Correct Answer:

The Universe is expanding.

  Question 643 out of 3 points

When astronomer's refer to inflation, they are discussing:Answer

Selected Answer:the rapid increase in the size of the very early Universe

Correct Answer:

the rapid increase in the size of the very early Universe

Response

Feedback:Correct, inflation was (possibly) a period of rapid expansion very early in

the history of the Universe leading to the extreme homogenaity and

isotropy of the Universe.

  Question 653 out of 3 points

Why do all the planets orbit the Sun in the same direction?

Answer

Selected

Answer: They formed from material all circulating in the same direction in the primordial Solar Nebula

Correct

Answer: They formed from material all circulating in the same direction in the primordial Solar Nebula

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Response

Feedback:Correct, the direction of rotation was set by the initial rotation of the

 primordial cloud.

  Question 663 out of 3 points

When astronomers discuss "metals" they are referring to:Answer

Selected Answer:

all elements except hydrogen and helium

Correct Answer:

all elements except hydrogen and helium

Response

Feedback:Correct, for historical reasons all elements except hydrogen and helium

are termed "metals" by astronomers.

  Question 673 out of 3 points

Which of the following has a linear size or radius closest to the radius of Betelguese?Answer

Selected Answer:

the orbit of Mars

Correct Answer:

the orbit of Mars

Response

Feedback:Correct, supergiant stars like Betelguese are extremely large (600-800

times larger than the Sun) and if located in the Solar system would engulfthe terrestrial planets and ateroids and reach almost to Jupiter.

  Question 681 out of 1 points

A Solar eclipse can occur only during a full Moon:Answer

Selected Answer: False

Correct Answer: False

Response

Feedback:Correct, remember a Solar eclipse is when the Moon is between the Sun

and the Earth and there for occurs during new Moon.

  Question 693 out of 3 points

How do the planets near the Sun differ from those farther out?Answer

Selected Answer:

The ones nearest the Sun are generally smallest

Correct Answer:

The ones nearest the Sun are generally smallest

Response Correct, remember that the Terrestrial planets are significantly smaller

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Feedback: than the Jovian planets. You might be tempted to say rotate faster by

remember that Jupiter rotates in only 10 hours.

  Question 700 out of 1 points

Compared to visible light, microwave radiation has much longer wavelengths and much

lower energies:Answer

Selected Answer: False

Correct Answer: True

Response

Feedback:Incorrect, microwave radiation is of much longer wavelengths than optical

light and thus of much lower energy since the energy of a photon is

inversly proportional to its wavelength.

  Question 710 out of 3 points

The modified form (by Newton) of Kepler's third law allows astronomers to determine

the mass of:Answer

Selected Answer:

all of the above

Correct Answer:

 planets around distant stars

Response

Feedback:Using the principles of Kepler and Newton, astronomers can determine the

masses of all of these objects. Einstein's General Relativity is used to

determine the properties of objects such as black holes and the Universe atlarge scales.

  Question 723 out of 3 points

Pluto is now classified as a dwarf planet because:Answer

Selected Answer:

it is in the Kuiper belt

Correct Answer:

it is in the Kuiper belt

Response

Feedback:

Correct, Pluto has not "cleared" its orbit as it is surrounded by similar

sized bodies.

  Question 733 out of 3 points

Mercury's atmosphere is likely non-existent because of its:Answer

Selected Answer:

small mass

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Correct Answer:

small mass

Response

Feedback:Correct, its small mass means that the gravitational force is not largeenough to retain gas molecules

  Question 743 out of 3 points

About how old is the Solar System?Answer

Selected Answer:

5,000,000,000 years

Correct Answer:

5,000,000,000 years

Response

Feedback:Correct, based upon radioactive dating of meteors the best estimate for

the age of the Solar system is 4.55 billion years.

  Question 750 out of 1 points

Type II supernovae are good standard candles:Answer

Selected Answer: True

Correct Answer: False

Response

Feedback:Incorrect, Type II supernovae are the final stage of a star of mass >8 *

M(Sun), and thus vary greatly in brightness depending on the star.

  Question 763 out of 3 points

Which of the following assumptions of the original nebular planet formation hypothesis

is likely untrue based upon observations of extra-Solar planets?Answer

Selected Answer:

The orbits of planets do not change after they are formed

Correct Answer:

The orbits of planets do not change after they are formed

Response

Feedback:Correct, the original models of planet formation assume that the planets do

not change their orbits, however observations of extra-Solar planets show

large gas giant planets very close to stars in very eccentric orbits suggestingthat they migrated in from further out.

  Question 770 out of 3 points

A white dwarf that exceeds the Chandrasekhar limit becomes:Answer

Selected Answer:

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a type II supernova

Correct Answer:

a type Ia supernova

Response

Feedback:

Incorrect, when a white dwarf exceeds 1.4 Solar masses electron

degeneracy pressure can no longer support it against gravity and so itcollapses and subsequently detonates and explodes as a Type Ia supernova

  Question 781 out of 1 points

The evolution of intellegent life on a planet is guarenteed once life forms:Answer

Selected Answer: False

Correct Answer: False

Response

Feedback:Correct, there is no reason to think that intellegent life (or even multi-

cellular life) will necessarily develop even if life forms on a planet.

  Question 791 out of 1 points

The Universe appears homogeneous and isotropic when averaged over large volumes:Answer

Selected Answer: True

Correct Answer: True

Response Feedback: Correct, while it may look very different in every direction,

  Question 800 out of 3 points

Astronomers are interested in particle accelerator experiments such as those conducted at

the Large Hadron Collider because:Answer

Selected

Answer: they will search for particles which may have led to the beginnings of

nuclear fusion in the center of stars

Correct

Answer: they will search for particles which may have led to inflation in the early

Universe

Response

Feedback:Incorrect, particle physics experiments like the LHC provide insight intothe conditions that must have existed in the early Universe.

  Question 11 out of 1 points

Compared to stars like the Sun, B stars like RigeL have:Answer

Selected Answer:

lifetimes much shorter than the Sun

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Correct Answer:

lifetimes much shorter than the Sun

Response

Feedback:Correct, hot, luminous massive stars like Rigel burn through there fuelmuch more quickly and thus have lifetimes much shorter than the Sun.

  Question 21 out of 1 points

What elements do astronomers consider metals or heavy elements? Answer

Selected Answer:

all elements besides hydrogen and helium 

Correct Answer:

all elements besides hydrogen and helium 

Response

Feedback:Correct, all elements but hydrogen and helium are called metals or

heavy elements

  Question 31 out of 1 points

The best evidence for dark matter in the Milky Way is:Answer

Selected

Answer: the higher than expected orbital velocities of stars and gas clouds at the

outskirts of the galaxy

Correct

Answer: the higher than expected orbital velocities of stars and gas clouds at theoutskirts of the galaxy

Response

Feedback:Correct, there appears to be more mass in the galaxy than can beaccounted for by the number of stars and gas clouds.

  Question 41 out of 1 points

Harlow Shapley concluded that the Sun was not located at the center of the Milky Way Galaxy by Answer

Selected Answer:

mapping the distribution of globular clusters in the galaxy. 

Correct Answer:

mapping the distribution of globular clusters in the galaxy. Response

Feedback:Correct, he used globular clusters in the halo of the Galaxy away from

the absorption of dust in the plane to determine the shape

  Question 51 out of 1 points

We infer a high mass black hole exists in the center of the Milky Way because:Answer

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Selected

Answer: we can watch the orbits of stars in the center and use Kepler's Third

Law

Correct Answer:

we can watch the orbits of stars in the center and use Kepler's Third

Law

Response

Feedback:Correct, by tracking the orbits of stars in the core of the Milky Way we can

apply Kepler's Third Law to determine the central mass, since it is very

massive (1,000,000 Solar masses) but located within a region ~1 AU across

it must be a black hole.

  Question 61 out of 1 points

Suppose that the calibration of the Cephiod period-luminosity relationship was uncertain

and resulted in distances uncertain by 30% in the Milky Way. What would we see in theuncertainties in distances to Cephieds in other galaxies:Answer

Selected Answer:

the uncertainty in distance would be at least 30%

Correct Answer:

the uncertainty in distance would be at least 30%

Response

Feedback:Correct, any uncertainty in the calibration of nearby objects results in atleast that uncertainty in more distant objects.

  Question 71 out of 1 points

Choose the best evidence that the disk of the Milky Way does not rotate like a solidwheel:Answer

Selected

Answer: stars in the disk have a similar velocity around the center (flat rotationcurve)

Correct Answer:

stars in the disk have a similar velocity around the center (flat rotationcurve)

Response

Feedback:

Correct, while the velocities are the same since the distances increase the

 periods must increase as you go out. A flat disk has the periods stay thesame throughout the disk and the velocities increase as you go out.

  Question 81 out of 1 points

If we see a high mass Ostar in the Andromeda galaxy tonight, we know that:Answer

Selected Answer:

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it will have already gone (Type II) supernova

Correct Answer:

it will have already gone (Type II) supernova

Response

Feedback:

Correct, remember that an O star has lifetime of order 1 million years, and

so even before the light from an O star reaches us from Andromeda (2million light years away) the star has been born, evolved, and exploded as aType II SN before any being in the MIlky Way can see it.

  Question 90 out of 1 points

Suppose the Hubble constant turned out to be 142 km/sec/mpc and not 71 km/sec/mpc.

How would that affect our estimate of the age of the Universe?Answer

Selected Answer:

The Universe would be about 30 billion yrs old.

Correct Answer:

The Universe would be about 7 billion yrs old.

  Question 101 out of 1 points

When we look at the Galactic center we see the stars as they were:Answer

Selected Answer:

25,000 years ago

Correct Answer:

25,000 years ago

Response

Feedback:Correct, 25,000 light years means that light takes 25,000 years toreach us.

  Question 111 out of 1 points

What is the diameter of the disk of the Milky Way? Answer

Selected Answer:

100,000 light years

Correct Answer:

100,000 light years

  Question 121 out of 1 points

What makes up the interstellar medium? Answer

Selected Answer:

gas and dust 

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Correct Answer:

gas and dust 

Response

Feedback:Correct, it is the gas and dust out of which new stars and planets

form

  Question 131 out of 1 points

Why are Cepheid variables important? Answer

Selected

Answer: Cepheids variables are pulsating stars whose pulsation periods are directly related to their true

luminosities. Therefore they can be used as distance indicators. 

Correct

Answer: Cepheids variables are pulsating stars whose pulsation periods are directly related to their true

luminosities. Therefore they can be used as distance indicators. 

Response

Feedback: Correct, they a pulsating stars whose periods are related to theirluminosities

  Question 141 out of 1 points

We can determine the age of a globular cluster by:Answer

Selected Answer:

finding the spectral types of the most luminous main sequence stars.

Correct Answer:

finding the spectral types of the most luminous main sequence stars.

ResponseFeedback:

Correct, the most massive/luminous main sequence stars left are the oneswhose lifetime is less than the age of the cluster, so the cluster must be just

older than that age.

All of the stars with lifetimes less than the age of the cluster will have

evolved off the main sequence already.

  Question 151 out of 1 points

The Sun's location in the Milky Way is:Answer

Selected Answer:in the disk about 2/3rds the way out from the center

Correct Answer:

in the disk about 2/3rds the way out from the center

Response

Feedback:Correct, we are about 25,000 light years from the center, and the Milky

Way is approximately 40-50,000 light years in radius.

  Question 16

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1 out of 1 points

An OB-star like Rigel moving through the Milky Way disk is a:Answer

Selected Answer:

Population I star

Correct Answer:

Population I star

Response

Feedback:Correct, "population I" refers to stars in the disk, "population II" to stars in

the halo (the oldest stars we currently see), and "population III to the starsthat must have formed first to provide the elements ("metals") we see in the

halo stars.

  Question 171 out of 1 points

Compared to stars in the disk like the Sun, stars in the halo of the galaxy formed:Answer

Selected Answer:

earlier, out of material less enriched in heavy elements

Correct Answer:

earlier, out of material less enriched in heavy elements

Response

Feedback:Correct, the halo stars formed before the majority of the supernovae wentoff to enrich subsequent generations of stars like the Sun.

  Question 181 out of 1 points

The Milky Way is:

Answer

Selected Answer:

the name of our Galaxy

Correct Answer:

the name of our Galaxy

Response

Feedback:Correct, that is the name given to our galaxy drawn from Greek

mythology.

  Question 191 out of 1 points

Where are most heavy elements made? Answer

Selected Answer:

In stars and supernovae 

Correct Answer:

In stars and supernovae 

Response Correct, the elements heavier than hydrogen and helium were made in

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Answer: The gravity exerted by the solar system and the Milky Way is strong enough to hold them

together against the expansion of the universe. 

Correct

Answer: The gravity exerted by the solar system and the Milky Way is strong enough to hold them

together against the expansion of the universe. 

Response

Feedback:Correct, objects bound together by gravity do no participate in the

expansion of the Universe

  Question 41 out of 1 points

Suppose the Hubble constant turned out to be 142 km/sec/mpc and not 71 km/sec/mpc.How would that affect our estimate of the age of the Universe?Answer

Selected Answer:

The Universe would be about 7 billion yrs old.

Correct Answer:

The Universe would be about 7 billion yrs old.

  Question 51 out of 1 points

What holds galaxy clusters together?Answer

Selected Answer:

The force of gravity.

Correct Answer:

The force of gravity.

  Question 61 out of 1 points

Why is the cosmic microwave background temperature so cool now?Answer

Selected

Answer: The expansion of the Universe has cooled the radiation and stretched its

wavelengths.

Correct

Answer: The expansion of the Universe has cooled the radiation and stretched its

wavelengths.

  Question 71 out of 1 points

Observations of the tiny irregularities in the cosmic microwave background support the

idea that the Universe:Answer

Selected Answer:

will expand forever.

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Correct Answer:

will expand forever.

  Question 81 out of 1 points

What do astronomers infer from the motion of the distant galaxies?Answer

Selected Answer:

The Universe is expanding.

Correct Answer:

The Universe is expanding.

  Question 91 out of 1 points

Why do we call dark matter "dark"? Answer

Selected Answer:

It emits little or no radiation of any wavelength. 

Correct Answer:

It emits little or no radiation of any wavelength. 

Response

Feedback:Correct, except gravitationally dark matter does interact strongly withlight at any wavelength

  Question 101 out of 1 points

The following pattern shows a:

Answer

Selected Answer:

isotropic but not homogeneous pattern

Correct Answer:

isotropic but not homogeneous pattern

Response

Feedback:Correct, it is isotropic (looking the same in all directions) but not

homogeneous (as it does not have uniform density).

  Question 11

1 out of 1 points

The following diagram shows a:

Answer

Selected Answer:

homogeneous but not isotropic pattern

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Correct Answer:

homogeneous but not isotropic pattern

Response

Feedback:Correct, it is homogeneous (having uniform density) but not isotropic asit looks different if you look up or down versus left and right.

  Question 121 out of 1 points

Which of the following methods used to determine the mass of a cluster of galaxies does not  depend on

 Newton's law of gravity? Answer

Selected Answer:

measuring the amount of distortion caused by a gravitational lens 

Correct Answer:

measuring the amount of distortion caused by a gravitational lens 

Response

Feedback:Correct, gravitational lenses depend on Einstein's theory of general

relativity  Question 13

1 out of 1 points

Suppose that we look at a photograph of many galaxies. Assuming that all galaxies formed at about the same

time, which galaxy in the picture is the youngest? Answer

Selected Answer:

the one that is farthest away 

Correct Answer:

the one that is farthest away 

ResponseFeedback:

Correct, the one furthest away from you is the one that is the furthestinto the past and so closest to the Big Bang

  Question 141 out of 1 points

I observe a galaxy that is 100 million light years away. Which of the following do I see? Answer

Selected Answer:

the light from the galaxy as it was 100 million years ago, and it is redshifted 

Correct Answer:

the light from the galaxy as it was 100 million years ago, and it is redshifted 

Response

Feedback:Correct, you see the galaxy as it was 100 million years ago since that is

how long it takes for the light to reach us and it will be redshifted as the

Universe is expanding do the galaxy will be moving away from us

  Question 151 out of 1 points

Type Ia supernovae make good "standard candles" because they are all formed by:Answer

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Selected Answer:

white dwarfs that exceed 1.4 Solar masses

Correct Answer:

white dwarfs that exceed 1.4 Solar masses

  Question 1 0 out of 3 points

The Hubble Space Telescope has taken the clearest views of the distant Universe because:Answer

Selected

Answer: it is above the atmosphere and thus is not covered in smog and clouds

Correct

Answer: it is above the atmosphere and thus above the blurring caused by

atmospheric motions

ResponseFeedback: Incorrect, the motions in the Earth's atmosphere "smear" out images,

telescopes in space are above this distorting effect

  Question 20 out of 3 points

What is a standard candle?Answer

Selected

Answer:[None Given]

Correct

Answer: an object of known brightness that can be used to measure the distance to

a cluster or galaxyResponse

Feedback:Incorrect, it is a variable star like a Cepheid (whose brightness we know

from its period) or an object like a Type-I supernova whose brightness weknow, so by comparing how bright it appears to how bright it intrinsically is

we can determineits distance via the inverse square law.

  Question 30 out of 3 points

About what temperature did the cosmic microwave background have at the time of its

formation?Answer

Selected Answer: [None Given]

Correct Answer:

3,000 K

Response

Feedback:Incorrect, when it formed the Universe had cooled to roughly 3,000 K,the temperature of the surface of a star.

  Question 40 out of 3 points

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Mercury's atmosphere is likely non-existent because of its:Answer

Selected Answer: [None Given]

Correct Answer:

small mass

Response

Feedback:Incorrect, its small mass means that the gravitational force is not largeenough to retain gas molecules

  Question 50 out of 3 points

What do we mean by inflation?Answer

Selected

Answer:[None Given]

Correct

Answer:

A sudden expansion of the universe driven by the energy released whenthe strong and electroweak forces froze out from the GUT force

Response

Feedback:Incorrect, inflation occurs early in the Universe's history when the

 physical forces become distinct.

  Question 60 out of 3 points

Which of the following is the best evidence for the existence of dark matter in the MilkyWay:Answer

Selected Answer: [None Given]

Correct Answer:

the orbital speeds of gas clouds outside the orbit of the Sun

Response

Feedback:Incorrect, see Figure 9-9 and the discussion beginning on page 181 in

the text.

  Question 70 out of 3 points

Which of the following assumptions of the original nebular planet formation hypothesis

is likely untrue based upon observations of extra-Solar planets?Answer

Selected Answer: [None Given]

Correct Answer:

The orbits of planets do not change after they are formed

Response

Feedback:Incorrect, the original models of planet formation assume that the planetsdo not change their orbits, however observations of extra-Solar planets

show large gas giant planets very close to stars in very eccentric orbits

suggesting that they migrated in from further out.

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  Question 80 out of 3 points

Why are objects like Mercury and the moons of Earth, Jupiter and Saturn so heavilycratered?Answer

SelectedAnswer:

[None Given]

Correct Answer:

Intense bombardment by asteroids and planetesimals subsequent to their birth

Response

Feedback:Incorrect, the impact of small bodies leads to cratering and without

tectonic activity, melting of ice or weathering the craters remain

  Question 90 out of 3 points

Uranus is peculiar because its:

Answer

Selected Answer: [None Given]

Correct Answer:

axis of rotation is so highly tilted

Response

Feedback:Incorrect, Uranus is tilted 98 degrees to its orbit and thus moves around

the Sun on its "side", but not the part of Uranus pointed at the Sun is not

always the same.

  Question 100 out of 3 points

How was the CMB (cosmic microwave background) created?Answer

Selected Answer: [None Given]

Correct Answer:

The burst of radiation from the big bang as it cooled toward 10,000 K.

Response

Feedback:Incorrect, when the radiation from the Big Bang cooled to about 10,000 Kthe hydrogen ions in the early Universe could combine with the electrons to

form neutral hydrogen allowing the radiation to escape and travel freely. It

has since been redshifted to radio wavelengths.

  Question 11

0 out of 3 points

The surface of Venus is mostly low density rock, while the average density is similar to

that of Earth, the interior of Venus must therefor be:Answer

Selected Answer: [None Given]

Correct Answer:

iron like the Earth

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Response Feedback: Incorrect, like the Earth Venus must have a high density iron core

  Question 120 out of 3 points

Incandescent light bulbs have a temperature of ~2700 K, this means that their light is

emitted mostly:Answer

Selected Answer: [None Given]

Correct Answer:

at infrared wavelengths

Response

Feedback:Incorrect, the cooler temperature (relative to the Sun) means that these bulbs emit most of their light at longer - infrared - wavelengths. This is

why they are so inefficient.

  Question 130 out of 3 points

A moon must be:Answer

Selected Answer: [None Given]

Correct Answer:

orbiting a planet

Response Feedback: Incorrect, by definition of a moon.

  Question 140 out of 3 points

Particle physicists are interested in the conditions in the early Universe because:Answer

Selected

Answer:[None Given]

Correct

Answer: this allows them to test unified field theories uniting the fundamental

forces of nature

Response

Feedback:Incorrect, the densities and energies in the early Universe cannot yet (andmay never) be replicated in particle accelerators

  Question 150 out of 3 points

As seen from the Moon, the Sun rises:Answer

Selected Answers: [None Given]

Correct Answers: d.

about once a month.

Response Incorrect, the Moon rotates in the same time it takes it to orbit the Earth

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Feedback: (~ one month), this is why we see only one side of the Moon.

  Question 160 out of 3 points

What factor about Mercury best explains its atmosphere or lack thereof?Answer

Selected

Answer:[None Given]

Correct Answer:

Its low mass has made it hard for it to retain any gases at all as anatmosphere.

Response

Feedback:Mercury has little atmosphere due to its low gravity (low mass) and

closeness to the Sun (and thus high temperature). Note that Mercury is arelatively slow rotating planet.

  Question 170 out of 3 points

We can measure the mass of the black hole at the center of the Milky Way galaxy by:Answer

Selected Answer: [None Given]

Correct Answer:

watching the orbits of stars in the center and using Kepler's Third Law

Response

Feedback:Incorrect, remember the following animation from class (image from the

UCLA Galactic Center group - This animation was created by Prof. Andrea

Ghez and her research team at UCLA and are from data sets obtained withthe W. M. Keck Telescopes." Image creators include Andrea Ghez, Angelle

Tanner, Seth Hornstein, and Jessica Lu).

  Question 180 out of 3 points

Compared to visible light, X-rays haveAnswer

Selected Answer: [None Given]

Correct Answer: d.

higher energy and shorter wavelengths

Response

Feedback:Incorrect, X-rays have very small wavelengths (1 nanometer) and very

high energies.

Remember that energy is inversely proportional to wavelength, so shorter

wavelength equals more energy, and one way to remember that X-rays are

more energetic is to remember that they can penetrate your body.

  Question 19

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0 out of 3 points

The modified form (by Newton) of Kepler's third law allows astronomers to determine

the mass of:Answer

Selected Answer: [None Given]

Correct Answer:

all of the above

Response

Feedback:Using the principles of Kepler and Newton, astronomers can determine the

masses of all of these objects. Einstein's General Relativity is used todetermine the properties of objects such as black holes and the Universe at

large scales.

  Question 200 out of 3 points

Astronomers are interested in particle accelerator experiments such as those conducted at

the Large Hadron Collider because:Answer

Selected

Answer:[None Given]

Correct

Answer: they will search for particles which may have led to inflation in the early

Universe

Response

Feedback:Incorrect, particle physics experiments like the LHC provide insight into

the conditions that must have existed in the early Universe.

  Question 210 out of 3 points

Which of the following has a linear size or radius closest to the radius of a white dwarf?Answer

Selected Answer: [None Given]

Correct Answer:

the Earth

Response

Feedback:Incorrect, a white dwarf is roughly the mass of the Sun squeezed into

the size of the Earth

  Question 220 out of 3 points

Dark energy is:Answer

Selected

Answer:[None Given]

Correct

Answer: inferred to exist because distant supernovae are fainter than the otherwise

should be due to the expansion of the Universe

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Response

Feedback:Incorrect, dark energy is what astronomers call the energy that is causing

the expansion of the Universe to accelerate, which results in distant

supernovae being even further from the Sun than they would be given dueto the expansion of the Universe.

  Question 230 out of 3 points

Tonight you observe the planet Saturn at midnight high in the Southern skies, you know

that:Answer

Selected Answer: [None Given]

Correct Answer:

Saturn and Earth must be on the same side of the Sun

Response Feedback: Incorrect, Saturn must be opposite the Sun at this point.

  Question 24

0 out of 3 points

The distribution of the dark matter in a spiral galaxy is Answer

Selected Answer: [None Given]

Correct Answer:

approximately spherical and about ten times the size of the galaxy halo 

Response Feedback: Incorrect, the spherical halo extends beyond the physical disk

  Question 250 out of 3 points

The Milky Way is:Answer

Selected Answer: [None Given]

Correct Answer:

the name of our Galaxy

Response

Feedback:Incorrect, the Milky Way is the name of our galaxy (from ancientGreek myths)

  Question 260 out of 3 points

A hot glowing solid will emitAnswer

Selected Answers: [None Given]

Correct Answers: c.

a continuous spectrum

Response

Feedback:Incorrect, a hot solid emits a continuous spectrum, approximately as a

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"blackbody".

  Question 270 out of 3 points

Clusters of galaxies are bound together by:Answer

Selected Answer: [None Given]

Correct Answer:

gravity

Response

Feedback:Incorrect, the attractive force of gravity binds together astronomical

objects from planets and stars to galaxies and clusters of galaxies

  Question 280 out of 3 points

When we look at the great galaxy in Andromeda we see it as it was approximately:Answer

Selected Answer: [None Given]

Correct Answer:

2.5 million years ago

Response

Feedback:Incorrect, the Andromeda galaxy (the nearest large galaxy to our ownMilky Way) is about 2.5 million light years away, and thus it takes light

2.5 million years to reach us.

  Question 290 out of 3 points

If we look at a galaxy 4.5 billion light years away we see it as it was:Answer

Selected Answer: [None Given]

Correct Answer:

when the Earth formed

Response

Feedback:Incorrect, remember the Earth formed roughly 4.5 billion years ago and it

takes light 4.5 billion years to travel 4.5 billion light years.

  Question 300 out of 3 points

The most important factor in determining a stars eventual fate is its:Answer

Selected Answer: [None Given]

Correct Answer:

mass

Response

Feedback:Incorrect, its mass is tied to the luminosity (since the star is in hydrostatic

equilibrium) and thus to the lifetime of the star.

  Question 31

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0 out of 3 points

Which of the following is not  evidence for dark matter? Answer

Selected Answer: [None Given]

Correct Answer:

the expansion of the universe 

Response Feedback: Incorrect, the expansion of the Universe is not driven by dark matter

  Question 320 out of 3 points

You observe a Cephied variable in a distant galaxy, you can now determine the galaxies:Answer

Selected Answer: [None Given]

Correct Answer:

distance

Response

Feedback:Incorrect, since Cephieds are standard candles we can use the apparent

 brightness (and their known absolute brightness) to calculate the distance

to the star (and thus galaxy)

  Question 330 out of 3 points

You have two blackbodies of the same size but differing luminosity, what statementmust be true?Answer

Selected Answer: [None Given]

Correct Answer:

the more luminous one is hotter

Response

Feedback:Incorrect, remember the luminosity goes as temperature to the fourth power

times the radius squared for a blackbody, and the the more luminous objectmust be hotter. This is why the hot O stars are so much more luminous than

cooler stars like the Sun.

  Question 340 out of 3 points

Dark matter is composed of:Answer

Selected Answer: [None Given]

Correct Answer:

no one knows for sure

Response Feedback: Incorrect, this is one of the current unsolved mysteries in astronomy

  Question 350 out of 3 points

What component of the primordial interstellar cloud became the inner planets?

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Answer

Selected Answer: [None Given]

Correct Answer:

The dust grains

ResponseFeedback: The inner planets were made from the dust grains in the early Solar

nebula which had clumped together to form planetesimals.

The ice and hydrogen gas were largely ejected from the inner Solar

system by the light and the Solar wind early in the formation of the Solarsystem.

  Question 360 out of 3 points

If we see a cluster with O and B stars we know that it:Answer

Selected Answer: [None Given]

Correct Answer:

must have formed recently

Response

Feedback:Incorrect, O and B stars have very short lifetimes and so must have

formed recently.

  Question 370 out of 3 points

Which of the following has a linear size or radius closest to the radius of Betelguese?Answer

Selected Answer: [None Given]

Correct Answer:

the orbit of Mars

Response

Feedback:Incorrect, supergiant stars like Betelguese are extremely large (600-800

times larger than the Sun) and if located in the Solar system would engulfthe terrestrial planets and ateroids and reach almost to Jupiter.

Remember the in class demo assumed the Sun was the size of a small ballwhen we said Betelguese was the size of the classroom.

  Question 380 out of 3 points

At present, what is the primary way that astronomers carry out SETI programs (that is, search for

extraterrestrial intelligence)? Answer

Selected Answer: [None Given]

Correct Answer:

 by using radio telescopes to search for signals from extraterrestrial civilizations 

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Response Feedback: Incorrect, we are searching for radio signals from intelligent life

  Question 390 out of 3 points

About how old is the Solar System?Answer

Selected Answer: [None Given]

Correct Answer:

5 billion years

Response

Feedback:Incorrect, the best evidence from the ages of rocks on Earth as well as the

asteroids coupled with models of the Sun's evolution yield an age of about4.55 billion years.

  Question 400 out of 3 points

When astronomers discuss "metals" they are referring to:

Answer

Selected Answer: [None Given]

Correct Answer:

all elements except hydrogen and helium

Response

Feedback:Incorrect, for historical reasons all elements except hydrogen and helium

are termed "metals" by astronomers.

  Question 410 out of 3 points

What is the largest object in the Solar System?Answer

Selected Answer: [None Given]

Correct Answer:

The Sun

Response

Feedback:Incorrect, the Sun conatins most of the mass of the Solar system

(~99%), as well as being 10x larger than the next largest object (Jupiter),if you answered the central black hole you are thinking of the galaxy.

  Question 420 out of 3 points

The greenhouse effect on Earth is currently:Answer

Selected

Answer:[None Given]

Correct Answer:

a largely natural process keeping the Earth at a temperature abovefreezing

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Response

Feedback:Incorrect, the greenhouse effect is important in keeping the Earth

habitable, but could potentially be dangerous to human civilization

  Question 430 out of 3 points

Pluto is now classified as a dwarf planet because:Answer

Selected Answer: [None Given]

Correct Answer:

it is in the Kuiper belt

Response

Feedback:Incorrect, Pluto has not "cleared" its orbit. Note that it croses Neptune'sorbit not that of Uranus.

  Question 440 out of 3 points

How does the observed density in stars compare with the critical density?

Answer

Selected Answer: [None Given]

Correct Answer:

it is much less

Response

Feedback:Incorrect, the density of material in stars averaged over the enormous

volume of space is much less than the density that required to close the

Universe (make it re-collapse), although the density of individual stars is

much larger than the critical density

  Question 450 out of 3 points

As seen from Earth, Jupiter cannot:Answer

Selected Answer: [None Given]

Correct Answer:

eclipse the Sun

Response Feedback: Incorrect, Jupiter cannot come between the Earth and the Sun

  Question 460 out of 3 points

Harlow Shapley concluded that the Sun was not located at the center of the Milky Way Galaxy by Answer

Selected Answer: [None Given]

Correct Answer:

mapping the distribution of globular clusters in the galaxy 

Response

Feedback:Incorrect, he used halo objects generally un-obscured by dust in the

 plane of the galaxy

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  Question 470 out of 3 points

Greenhouse gases warm a planet like Earth by:Answer

Selected Answer: [None Given]

Correct Answer:

retaining more infrared light emitted by the Earth

Response

Feedback:Incorrect, the radiation emitted by the Earth is at longer (infrared)

wavelengths compared to the Sun (optical), it is the retention of this

radiation that heats the Earth.

  Question 480 out of 3 points

Why is the cosmic microwave background temperature so cool now?Answer

Selected Answer: [None Given]

Correct Answer:

The expansion of the Universe has cooled it

Response

Feedback:The radiation has been redshifted (the wavelength of the radiation has beenstretched) and thus it is at lower energies - so the cosmic background

corresponds to a lower temperature blackbody.

  Question 490 out of 3 points

Which of the following methods used to determine the mass of a cluster of galaxies does not  depend on

 Newton's law of gravity? Answer

Selected Answer: [None Given]

Correct Answer:

measuring the amount of distortion caused by a gravitational lens 

Response

Feedback:Incorrect, gravitational lensing depends on Einstein's theory of general

relativity

  Question 500 out of 3 points

What produces the 21-cm radio line that we can be used to map the Milky Way Galaxy? Answer

Selected Answer: [None Given]

Correct Answer:

atomic hydrogen 

Response Feedback: Incorrect, the 21cm line comes from neutral hydrogen

  Question 510 out of 3 points

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Scale the Milky Way down to the size of a compact disc. Which of the following best describes the size, shape,

and distance of the Andromeda Galaxy on the same scale? Answer

Selected Answer: [None Given]

Correct Answer:

a compact disk a few meters away 

Response

Feedback:Incorrect, both are disk galaxies relatively (cosmically speaking) close

together

  Question 520 out of 3 points

Eris is classified as a dwarf planet (and not a planet) because:Answer

Selected Answer: [None Given]

Correct Answer:

it has not cleared its orbit around the SunResponse

Feedback:This is the only part of the definition of a planet that Eris does not meet, andit is "planet-like" in that it does have sufficient self-gravity to be round, and

it does orbit the Sun. However since it is within the Kuiper belt there are

numerous bodies near it that are of similar mass, so it has not "cleared its

orbit".

  Question 530 out of 3 points

Hydrostatic equilibrium means that:Answer

SelectedAnswer:

[None Given]

Correct

Answer: stars have a higher temperature and pressure in their centers to support the

mass of their outer layers

Response

Feedback:Incorrect, the concept of hydrostatic equilibrium implies that a star must

have a higher pressure in its center to support the weight of the outer

layers.

Despite the inclusion of "static" within this term, it does not imply that

nothing can move within a star - see for example convective transport of

energy.

  Question 540 out of 3 points

How does the interstellar medium obscure our view of most of the galaxy? Answer

Selected Answer: [None Given]

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Correct Answer:

The small mixture of dust grains in the interstellar medium absorbs visible light. 

Response

Feedback:Incorrect, interstellar dust grains absorb light and then re-radiates it inthe infrared

  Question 550 out of 3 points

When an atom absorbs a high energy photon and an electron is ejected we call this:Answer

Selected Answer: [None Given]

Correct Answer:

ionization

Response

Feedback:Incorrect, ionization is removing an electron from an atom (creating

an ion)

  Question 560 out of 3 points

As seen from Mars, the planets Mercury, Venus and Earth can only be seen in which of

the following locations in its sky:Answer

Selected Answer: [None Given]

Correct Answer:

 just above the eastern horizon before sunrise

Response

Feedback:Incorrect, from Mars, Earth (as well as Venus and Mercury) is an inner planet and so will be seen only near the Sun, all of the other points are

either on the opposite side of the sky from the Sun or not the same forevery person on the planet (the zenith).

  Question 570 out of 3 points

A white dwarf that exceeds the Chandrasekhar limit becomes:Answer

Selected Answer: [None Given]

Correct Answer:

a type Ia supernova

Response

Feedback:

Incorrect, when a white dwarf exceeds 1.4 Solar masses electron

degeneracy pressure can no longer support it against gravity and so itcollapses and subsequently detonates and explodes as a Type Ia supernova

  Question 580 out of 3 points

The moons of Mars were likely formed:Answer

Selected Answer: [None Given]

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Correct Answer:

in the asteroid belt before their later capture

Response Feedback: Incorrect, these irrgularly shaped objects are likely captured asteroids

  Question 59

0 out of 3 pointsWhy should galaxy collisions have been more common in the past than they are today? 

Answer

Selected Answer: [None Given]

Correct Answer:

Galaxies were closer together in the past because the universe was smaller. 

Response

Feedback:Incorrect, the Universe was much smaller so the force of gravity was

much larger (remember Newtons Law)

  Question 600 out of 3 points

A red giant star like Arcturus must have a:Answer

Selected Answer: [None Given]

Correct Answer:

luminosity much larger than the Sun

Response

Feedback:Incorrect, remember the Sun will eventually expand and cool to become a

red giant (and thus the other 3 answers must be wrong)

  Question 610 out of 3 points

When astronomer's refer to inflation, they are discussing:Answer

Selected Answer: [None Given]

Correct Answer:

the rapid increase in the size of the very early Universe

Response

Feedback:Incorrect, inflation was (possibly) a period of rapid expansion very earlyin the history of the Universe leading to the extreme homogenaity and

isotropy of the Universe.

  Question 620 out of 3 points

How do we know how old the Solar System is?Answer

Selected

Answer:[None Given]

Correct Answer:

By measuring the products of radioactive decay in old rocks and

meteors

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Response

Feedback:Incorrect, this is known as radiometric dating and uses many elements not just the

well-known carbon-14 method used to date relatively recent organic materials (such as

achaeological remains). 

  Question 630 out of 3 points

The cosmic microwave background shows that the Universe evolved from a:Answer

Selected Answer: [None Given]

Correct Answer:

hot dense state

Response

Feedback:Incorrect, the Hubble expansion shows that the Universe was once much

smaller while the cosmic microwave background must have been made of

much higher energy photons before they were redshifted by the expansionof the Universe.

  Question 640 out of 3 points

Using the Kepler satellite astronomers detect a planet with a semi-major axis of 1 AU

around a G2V star in Cygnus, its period will be:Answer

Selected Answer: [None Given]

Correct Answer:

1 year

Response

Feedback:Incorrect, a G2V star is like the Sun and the planet with a 1 AU orbit isthe Earth which has an orbital period of 1 year

  Question 650 out of 3 points

Which of the following is not  a possible solution to the Fermi Paradox? Answer

Selected

Answer:[None Given]

Correct

Answer: Given the current age of our galaxy, there has not been enough time for a galactic

civilization to develop. 

Response

Feedback:Incorrect, the Galactic disk has existed about twice as long as the

Sun  Question 66

0 out of 3 points

A Full Moon is at position:

Answer

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Selected Answer: [None Given]

Correct Answer:

e

Response

Feedback:Incorrect, a full Moon is when the Moon is on the opposite side of the

Earth from the Sun  Question 67

0 out of 3 points

The horizon is:Answer

Selected

Answer:[None Given]

Correct

Answer: an imaginary plane that separates what is visible in the sky from what is below the Earth

ResponseFeedback:

Incorrect, remember the horizon on Earth is the plane that separates whatyou can see from what you can't (this is why we call the distance out to

which we can see at any point in time in cosmology the "horizon")

  Question 680 out of 3 points

Which diagram shows the emission of the lowest energy photon?

Answer

Selected Answer: [None Given]

Correct Answer:

A

Response

Feedback:Incorrect, emission is when an electron goes from an outer (higher energy)

orbital to an inner (lower energy) orbital giving off energy in the form of a

 photon, the smaller the jump the less energy released.

  Question 690 out of 3 points

A main sequence star's luminosity comes from:Answer

Selected Answer: [None Given]

Correct Answer: e.

fusion of hydrogen into helium in the core

Response

Feedback:Incorrect, the main sequence is when a star uses nuclear fusion reactions toconvert hydrogen into helium in the core of the star.

Chemical burning (combining oxygen with other elements), stored

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gravitational energy and radioactive decay are not energy sources for main

sequence stars. Core helium

and shell hydrogen burning occur after the star has evolved off the mainsequence.

  Question 700 out of 3 points

An OB star like Rigel moving through the galactic disk is a:Answer

Selected Answer: [None Given]

Correct Answer:

Population I star

Response

Feedback:Incorrect, the name given to the stars of the Galactic disk is Population I,

the older stars of the halo are Pop II, and the first generation of stars

(which we have not yet discovered and may have all "died") are Pop III.

  Question 710 out of 3 points

We know of approximately how many exo-planets todayAnswer

Selected Answer: [None Given]

Correct Answer:

900

Response

Feedback:Correct, we currently know of about 900 extra-Solar planets (note 1 wasknown when I left graduate school 13 years ago)

  Question 720 out of 3 points

About how old is the Solar System?Answer

Selected Answer: [None Given]

Correct Answer:

5,000,000,000 years

Response

Feedback:Incorrect, based upon radioactive dating of meteors the best estimate for

the age of the Solar system is 4.55 billion years.

  Question 73

0 out of 3 points

The reason astronomers use near-infrared observations is to:Answer

Selected Answer: [None Given]

Correct Answer:

 penetrate interstellar dust clouds

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Response

Feedback:Incorrect, one of the key advantages of near-infrared is its ability to

 penetrate dust clouds where shorter wavelength opitcal light is absorbed.

Remember that dark matter does not interact with light and that hot gas

will emit at short wavelengths (high energies) in the X-rays and

ultraviolet.

  Question 740 out of 3 points

A sidereal day on Earth is not:Answer

Selected Answers: [None Given]

Correct Answers: c.

longer than a Solar day.

Response

Feedback:

Incorrect, all three of (a), (b), and (d) are true. The sidereal day is defined

in answer (a), and because the Earth orbits the Sun in the same direction itrotates the sidereal day is ~4 minutes shorter than the Solar day.

  Question 750 out of 3 points

Jupiter's composition is closest to that of:Answer

Selected Answer: [None Given]

Correct Answer:

the Sun

Response Feedback: Incorrect, both the Sun and Jupiter are mostly H and He

  Question 760 out of 3 points

The interstellar medium of galaxies today show more "metals" than that seen in distant

galaxies because:Answer

Selected

Answer:[None Given]

Correct Answer:

more supernovae have gone off to enrich the gasover the past few billion

yearsResponse

Feedback:Incorrect, remember two things:

1) when we look at distant galaxies we are seeing them as they were in the

 past

2) the Universe started out with H and He and no heavier elements like C, N, O, Si, Fethe "extra" few billion years that local galaxies mean that more

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supernovae go off and thus there are more metals (which are formed in

supernovae) in the galaxy.

Aside: remember to an astronomer all elements other than H and He are

"metals"

  Question 770 out of 3 points

The majority of the asteroids (the asteroid belt) lie between:Answer

Selected Answer: [None Given]

Correct Answer:

Mars and Jupiter

Response

Feedback:Incorrect, most of the asteroids lie in a "belt" between Mars and Jupiter,

while some have orbits which cross that of the Earth (or even Mercury)

most are in this region. Objects beyond Neptune are in the Kuiper belt orOort cloud.

  Question 780 out of 3 points

Why can't current theories describe what happened during the Planck era? Answer

Selected Answer: [None Given]

Correct Answer:

We do not yet have a theory that links quantum mechanics and general relativity. 

Response

Feedback:

Incorrect, despite the efforts of physicists over the last ~80 years we do

not yet have a theory linking quantum mechanics and gravity

  Question 790 out of 3 points

If astronomers on Earth see tonight a newly formed cluster of O stars in the Andromedagalaxy, alien astronomers in the Andromeda galaxy would most likely see (today) at the

same location:Answer

Selected Answer: [None Given]

Correct Answer:

a cluster of supernova remnants

Response

Feedback:Incorrect, remembering that O (and B) stars live fast and die young, so in

the 2 million years that the light from these stars took to reach the MilkyWay they will have evolved off the main sequence, become supergiants and

then become supernovae leaving behind black holes or white neutron stars.

  Question 800 out of 3 points

Why do we call dark matter "dark"? 

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Answer

Selected Answer: [None Given]

Correct Answer:

It emits, scatters or absorbs no or very little radiation of any wavelength. 

ResponseFeedback: Incorrect, it does not emit, scatter or absorb significant amounts of

light