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%\fancyfoot[LE,RO]{Ralf Kotulla}
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%% %\fancyhead[C]{Ralf Kotulla: Modeling explosive transient populations}
%% \fancyhead[L]{Scientific Data Processing \& Visualization in the cloud}
%% \fancyhead[R]{Ralf Kotulla: CIF21 DIBBs}














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\fancyhead[L]{Astronomy 103 - Final Exam}
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\begin{document}
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\begin{center}
\large\bf Astronomy 103 --  Final Exam --  December 17, 2014
\end{center}


%\bigskip
%{\bf Solutions: correct answers are marked in bold, red type.}

\bigskip
{\bf Instructions:  } 

{\bf No books, notes or calculator are allowed.} You have 2 hours to complete the exam, and please do not turn to the next page until instructed to do so.

%% {This exam consists of 50 questions. 45 correct questions correspond to a
%%   score of 100\%, i.e. 5 out of the 50 questions are bonus questions}

\bigskip
{\bf You may find the following information helpful:}

\begin{itemize}
\item{1 AU $=3\times10^8$ km}

\item{speed of light $c=3\times10^8$ m/s}

\item{Kepler's 3rd law: 
\[
a^3 = P^2 
\]
with the period $P$ in years and semi-major axis $a$ in AU.}

\item{Newton's law of gravity:
\[
F = \frac{GMm}{r^2}
\]}

\item{Peak wavelength and temperature of blackbody radiation:
\[
\lambda = \frac{3\times10^6}{T} \mbox{ nm}
\]
with wavelength $\lambda$ in nm (1 nm = $10^{-9}$ m) and temperature $T$ in
Kelvin.}

\item{Relationship between frequency $f$ and wavelength $\lambda$ of light:
\[
\lambda = \frac{c}{f}
\]}

\item{Conversion of mass into energy:  $E=mc^2$}

\item{Relationship between brightness $B$ and distance $d$:
\[
B_2 = B_1 \times \frac{d_1^2}{d_2^2}
\]}

\item{Relationship between luminosity $L$, temperature $T$ and radius $R$ of stars: 
\[
L=4\pi\sigma T^4 R^2
\]
where $4\pi \sigma$ are constants.}

\item Hubble's law:
\[ v = H \times d \]
where $v$ is velocity in km/s, $d$ is distance in Mpc, and $H$ is the Hubble
constant, $H=70$ km/s/Mpc.
\end{itemize}

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\newpage
%\begin{enumerate}[label=\arabic*.~, leftmargin=2em, itemsep=2ex]
\questions{1}


\item Which of the following choices lists the objects in order of increasing
  distance from the Sun?
\begin{enumerate}
\item Saturn, Venus, Proxima Centauri, the Andromeda Galaxy, the Virgo Cluster 
\item Proxima Centauri, Saturn, Venus, the Virgo Cluster, the Andromeda Galaxy 
\item The Virgo cluster, the Andromeda Galaxy, Proxima Centauri, Venus, Saturn 
\correctitem{Venus, Saturn, Proxima Centauri, the Andromeda Galaxy, the Virgo Cluster }
\item Venus, Saturn, Proxima Centauri, the Virgo Cluster, the Andromeda Galaxy
\end{enumerate}





\item Evaluate $(3\times10^4) \times (2\times10^7)$
\begin{enumerate}
\item $5 \times 10^{10}$ 
\item $5 \times 10^{11}$ 
\item $6 \times 10^{10}$ 
\correctitem{$6 \times 10^{11}$ }
\item $5 \times 10^{28}$
\end{enumerate}





\item The average temperature is hotter in summer than winter. This is
  ultimately caused by  
\begin{enumerate}
\item the fact that the Sun emits more energy per second in the summer than it does
in the winter 
\item the fact that the Earth is closer to the Sun in summer. 
\correctitem{the tilt of the Earth's axis relative to the Earth's orbit. }
\item the greenhouse effect that warms the Earth by trapping infrared radiation.
\end{enumerate}



\item Describe the daily motion of Polaris: 
\begin{enumerate}
\item It rises due east and sets due west once in every 24-hour period.
\item It moves eastward by slightly less than 1 degree per day. 
\correctitem{It stays nearly fixed in the northern sky above our North Pole.}
\item It rises due west and sets due east once in every 24-hour period.
\end{enumerate}





\item The Sun is directly over the equator on the 
\begin{enumerate}
\correctitem{at neither solstice }
\item summer solstice 
\item winter solstice 
\item at both solstices
\end{enumerate}



\newpage
%XXX
\item Where on Earth are you if Polaris is on your horizon? 
\begin{enumerate} 
\item  north pole 
\item  south pole 
\item  Tropic of Cancer 
\item  Tropic of Capricorn 
\correctitem{ equator}
\end{enumerate}





\item Willa is on the asteroid Xu. She starts from one pole of Xu and walks
without turning until she reaches a place where the stars appear to move in
horizontal circles, never rising or setting. If she has walked 10 km, what is
the circumference of Xu? 
\begin{enumerate}
\item 10 km 
\correctitem{20 km }
\item 40 km 
\item 100 km
\end{enumerate}





\item If the Moon's orbit were exactly in the plane of the Earth's orbit about
  the Sun, one would expect an eclipse of the Moon to occur about once every 
\begin{enumerate}
\item 2 weeks 
\item week 
\item never 
\correctitem{month }
\item year
\end{enumerate}





\item What causes the Moon's phases? 
\begin{enumerate}
\item The Earth's shadow covers part of the Moon. 
\correctitem{As the Moon orbits the Earth,
the part of the Moon that is lit is a changing fraction of the part that faces
the Earth. }
\item Depending on where the Moon is in its orbit, light from the Sun
lights up a larger or smaller part of the Moon's surface. 
\item The Earth interferes with the Sun's rays in a way that depends on where the Moon is in its
orbit.   
\end{enumerate}




%XXX
\item At full moon, as seen from the Earth, the Moon lies
\begin{enumerate} 
\correctitem{ opposite the Sun }
\item  90 degrees east of the Sun 
\item  90 degrees west of the sun 
\item  close to the Sun in the sky
\end{enumerate}




%XXX
\item A rock is in circular orbit about the Sun with a radius 4 AU.  What is its period?
\begin{enumerate} 
\item  1/16 year 
\item  1 year 
\item  2 years 
\item  4 years 
\correctitem{ 8 years}
\end{enumerate}





\item The ice planet Hoth has the same radius as the Earth but has 0.5 times the
  Earth's mass.  If you weigh 100 pounds on Earth, how many pounds would you
  weigh on Hoth? 
\begin{enumerate}
\item 25 pounds 
\correctitem{50 pounds }
\item 200 pounds 
\item 400 pounds
\end{enumerate}





\item The absorption lines of oxygen have the same wavelength as its emission
  lines. 
\begin{enumerate}
\correctitem{true }
\item false
\end{enumerate}




\item  The peak wavelength of the light from a star is 300 nm. What is the
  temperature of its surface?  
\begin{enumerate}
\item 300 K 
\item 1000 K 
\item 3000 K 
\correctitem{10,000 K }
\item 30,000 K 
\end{enumerate}





% XXX
\item When an object is heated, the light it emits is:
\begin{enumerate} 
\item  brighter and with longer average wavelength 
\item  dimmer and with longer average wavelength 
\correctitem{ brighter and with shorter average wavelength }
\item  dimmer and with shorter average wavelength
\end{enumerate}




\item  Light of which of the following kinds is observed by earthbound
  telescopes?  
\begin{enumerate}
\correctitem{radio waves and visible light }
\item visible light and x-rays
\item x-rays and gamma rays 
\item radio waves and x-rays  
\end{enumerate}




\item An electron jumps to a more distant orbit when an atom:  
\begin{enumerate}
\item emits light 
\correctitem{absorbs light }
\item electrons do not change orbits
\end{enumerate}





\item  An element can be identified by looking at its: 
\begin{enumerate}
\correctitem{spectral lines }
\item continuous spectrum 
\item gamma-ray bursts   
\end{enumerate}




\item Why are satellites used to detect x-rays? 
\begin{enumerate}
\item space-based detectors are more sensitive 
\item they avoid atmospheric turbulence 
\correctitem{air absorbs x-rays}
\end{enumerate}





\item When hydrogen fuses to helium, what fraction of its mass changes to
  energy?
\begin{enumerate}
\item 100\% 
\item 70\% 
\item 50\% 
\item 5\% 
\correctitem{0.7\%}
\end{enumerate}




\item The luminosity of a star is $9 \times 10^{25}$ watts.  How much mass does it change to
energy each second?  
\begin{enumerate}
\correctitem{$1 \times 10^{9}$ kg }
\item $3 \times 10^{9}$ kg 
\item $1 \times 10^{17}$ kg 
\item $3 \times 10^{17}$ kg 
\item $9 \times 10^{17}$ kg
\end{enumerate}





\item The primary source of the Sun's energy is  
\begin{enumerate}
\correctitem{fusion of light nuclei to make heavier ones }
\item fission of heavy nuclei into lighter ones 
\item the slow release of heat left over from the Sun's formation 
\item the solar magnetic field
\end{enumerate}





\item How many times more massive is the Sun than the Earth?  
\begin{enumerate}
\item 100 
\correctitem{300,000 }
\item 100 million
\end{enumerate}





\item About how hot is the Sun's photosphere?  
\begin{enumerate}
\item 3 K 
\item 300 K 
\item 3000 K 
\correctitem{6000 K}
\end{enumerate}




% XXX
\item The visible light we see from the Sun comes from what part of the Sun?
\begin{enumerate} 
\correctitem{photosphere }
\item corona 
\item chromosphere 
\item core
\end{enumerate}




\item The Sun is a stable star in which  
\begin{enumerate}
\item the rate at which energy is emitted by the core is equal to the rate at which energy is absorbed in the corona 
\item the rate of fusion equals the rate of fission 
\item radiation and convection balance one another 
\correctitem{gravity balances the force from pressure}
\end{enumerate}





% XXX
\item What is the most abundant element in the Sun?
\begin{enumerate} 
\correctitem{hydrogen}
\item helium
\item carbon
\item oxygen
\item iron
\end{enumerate}



\item Compared to a main-sequence star of type G, a main-sequence star of type B is:  
\begin{enumerate}
\item hotter and less massive 
\correctitem{hotter and more massive }
\item cooler and less massive 
\item cooler and more massive
\end{enumerate}




% XXX
\item Which of the following lists gives the spectral types of stars in order from the type corresponding to stars with the hottest surfaces to the type corresponding to stars with the coolest surfaces?
\begin{enumerate} 
\item F, B, G, O, M 
\item A, B, F, G, O 
\correctitem{O, B, F, G, M }
\item K, M, F, G, B 
\item B, G, F, M, K
\end{enumerate}



% XXX
\item Star A appears brighter than star B, as seen from Earth. Therefore, start A must be closer to Earth than star B.
\begin{enumerate} 
\item True
\correctitem{False}
\end{enumerate}




\item Stars of spectral class M do not show strong lines of hydrogen in their spectra because  
\begin{enumerate}
\item they contain very little hydrogen 
\correctitem{their surfaces are so cool that most hydrogen is in the ground state }
\item their surfaces are so hot that most hydrogen is ionized 
\item the hydrogen lines are swamped by even stronger lines of other elements
\end{enumerate}





\item Compared to a star with mass equal to the mass of the Sun, a main sequence star of 10 solar masses is:  
\begin{enumerate}
\item cooler and less luminous 
\item cooler and more luminous 
\item hotter and less luminous 
\correctitem{hotter and more luminous}
\end{enumerate}





\item What is plotted on an H-R diagram?  
\begin{enumerate}
\item luminosity versus mass 
\correctitem{luminosity versus surface temperature }
\item mass versus surface temperature 
\item mass versus abundance of hydrogen, or 
\item none of these is correct
\end{enumerate}




\enlargethispage{2em}
\item About what fraction of stars are on the main sequence?  
\begin{enumerate}
\item less than 10\% 
\item about 50\% 
\correctitem{more than 90\%}
\end{enumerate}





\item Stars with cool surfaces can be very luminous if they are very  
\begin{enumerate}
\item small 
\item hot 
\correctitem{large }
\item close to our solar system 
\end{enumerate}




\item Saturn is 10 AU from the Sun. The brightness of sunlight on the Earth is about 1400 watt/meter$^2$ .  What is the brightness of sunlight on Saturn?    
\begin{enumerate}
\item 140 watt/meter$^2$ 
\correctitem{14 watt/meter$^2$ }
\item 1.4 watt/meter$^2$ 
\item 0.14 watt/meter$^2$ 
\end{enumerate}





\item Two clouds of interstellar gas, A and M, contract to form stars.  Suppose
  that no mass is lost in the contraction and that when they stop contracting,
  cloud A is a type A star and cloud M is a type M star.  Compared to cloud M,
  cloud A has:  

\begin{enumerate}
\item a larger percentage of hydrogen 
\item a smaller percentage of hydrogen 
\correctitem{more mass }
\item less mass
\end{enumerate}



%% \newpage
%% % XXX
%% \item When visible light from a star passes through interstellar dust, the light
%% \begin{enumerate} 
%% \item ionizes the dust, which then emits blue and ultraviolet light
%% \item is dimmed and becomes bluer
%% \correctitem{is dimmed and reddened}
%% \item primarily excites electrons in the silicon atoms of the dust. We observe
%% ultraviolet light when the electrons fall back to their ground state.
%% \item is Doppler shifted
%% \end{enumerate}





\item A main-sequence star with a mass of 15 times the mass of the Sun has a lifetime that is  
\begin{enumerate}
\item much longer than the Sun's. 
\correctitem{much shorter than the Sun's. }
\item about the same as the Sun's.
\end{enumerate}





\item When visible light from a star passes through interstellar dust, the light  
\begin{enumerate}
\item ionizes the dust, which then emits red and infrared light 
\item ionizes the dust, which then emits blue and ultraviolet light 
\item is dimmed and becomes bluer 
\item is Doppler shifted 
\correctitem{is dimmed and reddened}
\end{enumerate}





%% For questions 32-35, choose one of the four energy-producing processes listed below.  
%% \begin{enumerate}
%% \item Contraction of the core and fusion of hydrogen to helium in a shell 
%% \item Fusion of helium to carbon in the core 
%% \item Contraction of the entire star 
%% \item Fusion of hydrogen to helium in the core
%% \end{enumerate}




\enlargethispage{3ex}
\item What is the source of energy of a protostar, before it has reached the main
sequence?  
\begin{enumerate}
\item Contraction of the core and fusion of hydrogen to helium in a shell 
\item Fusion of helium to carbon in the core 
\correctitem{Contraction of the entire star }
\item Fusion of hydrogen to helium in the core
\end{enumerate}


\item Which is the energy source of a star in its first red-giant stage? 
\begin{enumerate}
\correctitem{Contraction of the core and fusion of hydrogen to helium in a shell }
\item Fusion of helium to carbon in the core 
\item Contraction of the entire star 
\item Fusion of hydrogen to helium in the core
\end{enumerate}


\item Which provides the energy of a main sequence star? 
\begin{enumerate}
\item Contraction of the core and fusion of hydrogen to helium in a shell 
\item Fusion of helium to carbon in the core 
\item Contraction of the entire star 
\correctitem{Fusion of hydrogen to helium in the core}
\end{enumerate}


\item Which of these is an energy source for a star just after the helium flash?
\begin{enumerate}
\item Contraction of the core and fusion of hydrogen to helium in a shell 
\correctitem{Fusion of helium to carbon in the core }
\item Contraction of the entire star 
\item Fusion of hydrogen to helium in the core
\end{enumerate}


%% For questions 36-69, identify the description with one of the four choices below.  
%% \begin{enumerate}
%% \item Type II supernova 
%% \item Type I supernova 
%% \item Planetary nebula 
%% \item Nova
%% \end{enumerate}





\item What is the ejected outer part of a star whose core becomes a white dwarf. 
\begin{enumerate}
\item Type II supernova 
\item Type I supernova 
\correctitem{Planetary nebula }
\item Nova
\end{enumerate}


\item What is the explosion that results from hydrogen from a companion star falling onto
a white dwarf and suddenly fusing to helium when it gets hot enough to ignite.
\begin{enumerate}
\item Type II supernova 
\item Type I supernova 
\item Planetary nebula 
\correctitem{Nova}
\end{enumerate}


\item What is the explosion that results from the gravitational collapse of the iron core
of a massive star when it approaches its upper mass limit. 
\begin{enumerate}
\correctitem{Type II supernova }
\item Type I supernova 
\item Planetary nebula 
\item Nova
\end{enumerate}



\item What is the explosion
that results from the gravitational collapse of a white dwarf when it approaches
or reaches its upper mass limit.  
\begin{enumerate}
\item Type II supernova 
\correctitem{Type I supernova }
\item Planetary nebula 
\item Nova
\end{enumerate}



\item One billion years from now the Sun will be a  
\begin{enumerate}
\item red giant 
\correctitem{main-sequence star }
\item white dwarf 
\item none of the above
\end{enumerate}



\item What is the next stage in the Sun's evolution?  
\begin{enumerate}
\correctitem{red giant }
\item neutron star 
\item type F main-sequence star 
\item white dwarf 
\item red dwarf
\end{enumerate}




%% For questions 42-45, match the following people to their discoveries.  
%% \begin{enumerate}
%% \item Chandrasekhar 
%% \item Franz Zwicky and Walter Baade 
%% \item Jocelyn Bell and Antony Hewish 
%% \item Annie Jump Cannon
%% \end{enumerate}





\item Who found the upper limit on the mass of white dwarfs 
\begin{enumerate}
\correctitem{Chandrasekhar }
\item Franz Zwicky and Walter Baade 
\item Jocelyn Bell and Antony Hewish 
\item Annie Jump Cannon
\end{enumerate}


\item Who first to discover pulsars. 
\begin{enumerate}
\item Chandrasekhar 
\item Franz Zwicky and Walter Baade 
\correctitem{Jocelyn Bell and Antony Hewish }
\item Annie Jump Cannon
\end{enumerate}


\enlargethispage{3ex}
\item Who classified the spectra of 400,000 stars. 
\begin{enumerate}
\item Chandrasekhar 
\item Franz Zwicky and Walter Baade 
\item Jocelyn Bell and Antony Hewish 
\correctitem{Annie Jump Cannon}
\end{enumerate}


\item Who first proposed that supernovae were the result of the gravitational collapse
of a star to form a neutron star. 
\begin{enumerate}
\item Chandrasekhar 
\correctitem{Franz Zwicky and Walter Baade }
\item Jocelyn Bell and Antony Hewish 
\item Annie Jump Cannon
\end{enumerate}




\item The fastest-spinning neutron star known rotates about  
\begin{enumerate}
\item once a day 
\item once an hour 
\item once a second 
\item 30 times a second 
\correctitem{700 times a second}
\end{enumerate}




\item A black hole is likely to be the end of stellar evolution for what type of mainsequence star?  
\begin{enumerate}
\item A 
\item G 
\item M 
\correctitem{O}
\end{enumerate}





% XXX
\item What can escape from within a black hole? 
\begin{enumerate}
\correctitem{Neither light nor matter }
\item Light only 
\item Both light and matter 
\item Matter only
\end{enumerate}





\item Compared to terrestrial planets, Jovian planets are  
\begin{enumerate}
\item larger and denser 
\item smaller and denser 
\correctitem{larger and less dense}
\item smaller and less dense  
\end{enumerate}




\newpage
\item Most of the solar system's mass is in  
\begin{enumerate}
\item comets 
\item asteroids 
\item planets 
\item meteoroids 
\correctitem{the Sun}
\end{enumerate}






\item Why do all of the planets have orbits that lie in nearly the same plane and that are in the same direction -- counterclockwise looking down on the solar system from far above the Earth's North Pole?  
\begin{enumerate}
\item When they were captured by the Sun, the Sun was moving past a cluster of
planets, and all of those planets were on one side of its path.  
\item Shortly
after they formed, the planets were moving in random directions.  In the 4 1/2
billion years since then, the Sun's gravity has pulled them into the same plane
\correctitem{The planets and Sun all formed from a cloud of gas and dust  that contracted
as it cooled. As the cloud contracted, its spin increased and it flattened. By
the time the planets formed, the cloud was a flat spinning disk.  }
\end{enumerate}




\item The Earth's atmosphere is primarily  
\begin{enumerate}
\correctitem{nitrogen and oxygen }
\item nitrogen and water vapor 
\item carbon dioxide and oxygen 
\item water vapor and carbon dioxide 
\item methane and ammonia
\end{enumerate}
%% For questions 52-55, choose one of the planets below.  
%% \begin{enumerate}
%% \item Mars 
%% \item Mercury 
%% \item Earth 
%% \item Venus 
%% \item None of these
%% \end{enumerate}





\item The terrestrial planet whose crater-covered surface most closely resembles
the Moon's.  
\begin{enumerate}
\item Mars 
\correctitem{Mercury }
\item Earth 
\item Venus 
\item None of these
\end{enumerate}




\item Because of the greenhouse effect, this planet has the hottest surface in the
solar system. 
\begin{enumerate}
\item Mars 
\item Mercury 
\item Earth 
\correctitem{Venus }
\item None of these
\end{enumerate}




\item The planet that is closest in size to the Earth (not including
the Earth itself).  
\begin{enumerate}
\item Mars 
\item Mercury 
\item Earth 
\correctitem{Venus }
\item None of these
\end{enumerate}




\item Which of these is the smallest of the terrestrial planets. 
\begin{enumerate}
\item Mars 
\correctitem{Mercury }
\item Earth 
\item Venus 
\item None of these
\end{enumerate}



% XXX
\item They often pass the Sun once and then leave the solar system.
\begin{enumerate}
\correctitem{comets }
\item meteoroids 
\item asteroids 
\end{enumerate}





\item Jupiter-mass planets that are found very close to their parent stars are called:  
\begin{enumerate}
\item Superearths 
\correctitem{Hot Jupiters }
\item Goldilocks planets 
\item Cold Jupiters
\end{enumerate}





% XXX
\item Comet tails extend from the comet in what direction? 
\begin{enumerate}
\correctitem{away from the Sun }
\item away from the Sun when the comet is approaching the Sun and toward the Sun
when the comet is moving away 
\item toward the Sun
\end{enumerate}





\item Which one of these methods is not a way to find planets around stars other than the Sun?  
\begin{enumerate}
\correctitem{radar }
\item radial velocity 
\item transits 
\item microlensing   
\end{enumerate}




\item A quasar is thought to be powered by  
\begin{enumerate}
\item collisions of stars in the the galaxy's core 
\item radiation from supermassive stars 
\item supernovae triggered by density waves in the galaxy's bulge 
\correctitem{radiation from matter accreting onto a supermassive black hole}
\end{enumerate}





\item In what century were galaxies first shown to lie outside the Milky Way?  
\begin{enumerate}
\item 5th century BC 
\item 17th century 
\item 18th century 
\item 19th century 
\correctitem{20th century}
\end{enumerate}





%% For questions 60-63, choose one of the three types of galaxy below.  
%% \begin{enumerate}
%% \item elliptical galaxies 
%% \item irregular galaxies 
%% \item spiral galaxies
%% \end{enumerate}





\item These galaxies have little gas and dust and few new stars. 
\begin{enumerate}
\correctitem{elliptical galaxies }
\item irregular galaxies 
\item spiral galaxies
\end{enumerate}




\item These galaxies have new stars in their disk. 
\begin{enumerate}
\item elliptical galaxies 
\item irregular galaxies 
\correctitem{spiral galaxies}
\end{enumerate}




\item These galaxies have new stars but no disk. 
\begin{enumerate}
\item elliptical galaxies 
\correctitem{irregular galaxies }
\item spiral galaxies
\end{enumerate}




\item These are the reddest of the three types of galaxies. 
\begin{enumerate}
\correctitem{elliptical galaxies }
\item irregular galaxies 
\item spiral galaxies
\end{enumerate}



\newpage
\item Spiral and irregular galaxies are bluer than elliptical galaxies because  
\begin{enumerate}
\item they have smaller redshifts. 
\correctitem{unlike elliptical galaxies, they have young O and B stars. }
\item unlike elliptical galaxies, they have almost no O and B stars. 
\item The question is misleading, because irregular galaxies are redder than ellipticals.
\end{enumerate}





% XXX
\item Most of the mass of the Milky Way galaxy is 
\begin{enumerate}
\item in the spiral arms 
\item in the disk, but not in the spiral arms 
\item in the nuclear bulge 
\correctitem{invisible and in the halo }
\item in the brightest, most massive stars of halo
\end{enumerate}





% XXX
\item How are galaxies spread out throughout the universe
\begin{enumerate}
\item They are grouped into clusters that are spread more-or-less evenly throughout space
\correctitem{They are grouped into clusters that in turn are clumped into superclusters}
\item Galaxies are densest near us, and become more spread out as we look further out
\item Galaxies are densest near a distant point in space, which can be interpreted as
the center of the universe, and are ore spread out as one looks way from that
point.
\end{enumerate}





\item Hubble's law states that  
\begin{enumerate}
\correctitem{the speed at which galaxies move away from us is proportional to their
distance from us. }
\item all galaxies move away from us at the same uniform speed
\item the redshift of galaxies is proportional to the speed at which they move away
from us 
\item the redshift of galaxies is proportional to the speed at which they
move toward us 
\item anything that can go wrong with an astronomical observation
will go wrong    
\end{enumerate}




\item A galaxy is moving away from us at 7000 km/s. How far away is it?  Use Hubble's constant of 70 km/s/Mpc. 
\begin{enumerate}
\correctitem{100 Mpc }
\item 1000 Mpc 
\item 4900 Mpc 
\item 490,000 Mpc
\end{enumerate}




\newpage
\item  The Local Group is  
\begin{enumerate}
\item a cluster of galaxies including M87 
\correctitem{a cluster of galaxies including the Milky Way }
\item a cluster of stars including the Sun and alpha Centauri 
\item a globular cluster  
\end{enumerate}




\item The rotation curve of a galaxy is  
\begin{enumerate}
\correctitem{the orbital speed of stars and gas around a galaxy at different radii from
the center. }
\item the shape of the orbits of stars around a galaxy. 
\item the rotation of dark matter around a galaxy. 
\item a measurement that shows that all the matter
in a galaxy is due to stars. 
\end{enumerate}




\item  Because of the presence of dark matter, the rotation curve of galaxies  
\begin{enumerate}
\item goes down at large radius 
\item goes up at large radius 
\correctitem{flattens at large radius }
\item none of the above.
\end{enumerate}



\item From the velocity of galaxies in galaxy cluster, we can tell that most of the mass of the cluster is in  
\begin{enumerate}
\item intracluster gas 
\correctitem{dark matter }
\item dark energy 
\item galaxies   
\end{enumerate}



% XXX
\item Why is 21 cm radio emission useful for studying the structure of the Milky Way
\begin{enumerate}
\item The waves penetrate dusty cocoons to reveal star formation
\item The waves are not absorbed by Galactic black holes
\correctitem{It can be used to map the hydrogen gas in the spiral arms}
\item Radio waves provide a distance measurement like parallax
\end{enumerate}




\item  The intracluster gas in a galaxy cluster  
\begin{enumerate}
\item is the hot gas between galaxies in a galaxy cluster 
\item contains most of the ordinary matter in a galaxy cluster 
\item is smaller than the amount of matter
needed to explain the velocities of galaxies in a galaxy cluster 
\correctitem{all of the above }
\end{enumerate}




\item Which of these is evidence for dark matter?  
\begin{enumerate}
\item rotation curves of galaxies 
\item velocity of galaxies in galaxy clusters 
\item gravitational lensing 
\correctitem{all of the above}
\end{enumerate}






\item Galaxy collisions  
\begin{enumerate}
\item induce star formation in the galaxies 
\item change galaxies of one type to another 
\item can drive gas to the central supermassive black holes 
\correctitem{all of the above}
\end{enumerate}




\item Major mergers between galaxies typically  
\begin{enumerate}
\item make irregular galaxies 
\item make spiral galaxies 
\correctitem{make elliptical galaxies }
\item make dwarf galaxies
\end{enumerate}




\item The process by which galaxies form from merging smaller galaxies is called  
\begin{enumerate}
\item galactic acquisition 
\correctitem{hierarchical merging }
\item dark matter 
\item quasar epoch
\end{enumerate}





\item Large surveys of galaxies shows that galaxies are distributed  
\begin{enumerate}
\item evenly across the universe 
\correctitem{in large filaments separated by voids }
\item in small clumps 
\item at random
\end{enumerate}



\enlargethispage{3ex}
\item The galactic distances used to measure the acceleration of the universe are determined using  
\begin{enumerate}
\correctitem{the brightness of Type Ia supernovae }
\item Hubble's law 
\item the brightness of main-sequence stars (spectroscopic parallax) 
\item parallax 
\item the period-luminosity relation of Cepheid variables
\end{enumerate}




\item  The age of the universe is estimated to be  
\begin{enumerate}
\item less than the Earth's age 
\item the same age as the Sun 
\correctitem{about 14 billion years }
\item 6.2 trillion years   
\end{enumerate}



\item  The cosmic microwave background is  
\begin{enumerate}

\correctitem{leftover radiation from the Big Bang }
\item proof that the universe is getting warmer 
\item a result of the hot intergalactic gas between clusters 
\item the observable form of dark energy
\end{enumerate}




\item  Which of the following elements were created in stars and not created in the Big Bang?  
\begin{enumerate}
\item helium 
\item deuterium 
\correctitem{carbon}
\end{enumerate}






% XXX
\item Most of the energy content of the universe is in
\begin{enumerate}
  \item normal matter
  \item dark matter
  \correctitem{dark energy}
  \item Normal matter, dark matter and dark energy contribute equal fractions to
    the energy content of the universe
\end{enumerate}



\item  Compared to the universe today, the early universe was  
\begin{enumerate}
\correctitem{hotter and denser }
\item cooler and less dense 
\item hotter and less dense 
\item cooler and denser
\end{enumerate}



\item  By measuring the size of spots in the cosmic microwave background, we can tell that the universe is   
\begin{enumerate}
\item closed 
\item curved 
\correctitem{flat }
\item open
\end{enumerate}





\item  Which two problems in our model of the universe does the theory of inflation solve?  
\begin{enumerate}
\item the acceleration of the universe and the horizon problem 
\correctitem{the horizon problem and the flatness problem }
\item the flatness problem and the origin of dark matter 
\item the origin of dark matter and the acceleration of the universe
\end{enumerate}






\item  The universe is observed to be   
\begin{enumerate}
\item coasting 
\correctitem{accelerating }
\item deaccelerating 
\item contracting
\end{enumerate}





\item  Olber's paradox is resolved by   
\begin{enumerate}
\correctitem{the finite age of the universe }
\item the mass-luminosity relation 
\item the cosmic microwave background 
\item the period-luminosity relation
\end{enumerate}





\end{enumerate}

\label{lastpage}

\end{document}
