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8/13/2019 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