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Sample Final Exam Solutions
Astronomy A-100 Fall 2007
Dr. Edward Rhoads
Note: this is what I did last year, the 2007 final will consist of 60 multiple choice worth 3
pts each and 8 short answer questions each worth 15 points.
1) You get a brand new car. The first night you own it (and park it outside) it is hit by a
basketball size meteorite. Alas, your insurance does not cover meteorites! How do
you react?
a) Get upset that your insurance company does not recognize astronomical events as
a reason for a claim.
b) Sue the insurance company.
c) Get depressed that you have that bad of luck.
d) Do a dance of joy – you are rich!
2) What are the densities of asteroids?
a) about 25% that of water
b) about the density of water
c) about three times the density of water
d) all of the above
3) Where do the “Trojan” asteroids lie?
a) on the orbit of Mars
b) between the orbits of Mars and Jupiter
c) on the orbit of Jupiter
d) all of the above
4) How are asteroids found?
a) they have a unique color
b) you watch for movement with respect to background stars
c) by looking for a star that “pulsates”
d) you don’t find them, they find you
5) Why do asteroids have a much higher percentage of gold in them than you find in the
crust of the earth?
a) we have mined most of the gold out of the earth’s crust (thus it is rare)
b) the earth received a smaller percentage of gold than the rest of the solar system
c) asteroids received a larger percentage of gold than the rest of the solar system
d) most of the earth’s gold sank to the core
6) What is the culprit behind the Kirkwood gaps in the main asteroid belt (regions where
there are almost no asteroids)?
a) orbital resonances with Jupiter
b) tidal interactions with the sun
c) larger asteroids cleared out these regions
d) harmonic resonances created by the sun’s depression of space time
7) Does Jupiter have a “solid” region?
a) no
b) yes, but tens of thousands of miles beneath the atmosphere
c) yes, but a few hundred miles below the atmosphere
d) I really need to learn to not copy off of my neighbor
8) How does the energy Jupiter emits in the infrared compare with the amount of energy
Jupiter absorbs from sunlight?
a) emits half as much IR energy
b) emits same
c) emits twice as much IR energy
d) Jupiter does not absorb any sunlight
9) For question 8, what is the source of the energy which Jupiter emits in the infrared?
a) winds
b) the sun
c) hydrogen rain
d) rotational energy
10) What causes the bands in the atmosphere of Jupiter?
a) land masses
b) atmospheric circulation
c) storms
d) solar winds
11) What is the Great Red Spot?
a) a giant hurricane
b) a meteorite crater
c) a moon which orbits Jupiter at the same rate which it rotates (thus seems to be in
the same spot)
d) another term for the south pole of Jupiter
12) What is Jupiter mostly made of?
a) Iron
b) Oxygen
c) Hydrogen
d) Helium
13) Why is Io the most volcanic object in the solar system?
a) tidal heating
b) collisions with comets have melted it
c) collisions with asteroids have melted it
d) heating by the core from radioactive decay
Questions 14 and 15 refer to the image below:
14) What is the explanation for that protrusion above Io on the left hand side?
a) a large cloud
b) a flaw in the image
c) a large formation of rocks
d) a volcanic plume
15) What does the shape and size of this protrusion tell us about Io?
a) Io has an atmosphere
b) Io has no atmosphere
c) Io rotates very quickly
d) none of the above
16) Why does Europa have a giant liquid ocean underneath a thick layer of surface ice?
a) tidal heating
b) collisions with comets have melted it
c) collisions with asteroids have melted it
d) heating by the core from radioactive decay
17) Why does the atmosphere of Saturn have a much lower amount of Helium than we
expect it to have because of solar abundances?
a) Saturn is not big enough to collect and hold onto Helium
b) Saturn’s Helium rains into the core
c) the Helium has been changed into other elements
d) TRICK! Saturn has as much Helium as we expect it to have.
18) What is the average density of Saturn?
a) about 70% of the density of water
b) about the density of water
c) about 30% greater than the density of water
d) twice the density of water
19) How dense are the rings of Saturn?
a) about the density of water (rocks crashing together)
b) 9.3% the density of water
c) 0.3% the density of water
d) an icy fog (0.03% that of water)
20) How thick are most of the rings of Saturn?
a) 5-30 m
b) 500-1000 m
c) 10-30 miles
d) 100-300 miles
21) What causes the “gaps” in Saturn’s rings?
a) harmonic resonances created by Saturn’s depression of space time
b) tidal interactions with Saturn
c) orbital resonances with moons
d) some parts of the rings absorb more sunlight and only appear to be dark
22) Which moon has the thickest atmosphere?
a) Triton
b) Titan
c) Io
d) Enceladus
23) Why is Enceladus the best place in the solar system to ski?
a) It has lots of craters
b) It has lots of mountains
c) It has volcanoes which cover parts of it in fresh snow
d) It has the most ancient ice in the solar system
24) What is the source for Saturn’s newly discovered E ring?
a) Tidal break up of a recent comet.
b) Collisions of Shepard moons with Pan.
c) The volcanoes of Enceladus.
d) The atmosphere of Titan leaking out.
25) Which of the following have we found evidence for on Titan?
a) methane rivers
b) water rivers
c) sulfur spewing volcanoes
d) all of the above
26) Which of the following is true about Uranus?
a) there are no seasons on Uranus because it is too far from the sun
b) Uranus has no rings
c) Uranus is tilted on its side
d) Uranus currently has the most known moons in the solar system
27) How is Uranus different from Jupiter and Saturn?
a) Uranus has no moons
b) Uranus’s core is different
c) Uranus has a lower density
d) Uranus does not have Hydrogen or Helium in its atmosphere
Question 28 refers to the image below (of Miranda, moon of Uranus):
28) Miranda looks like this because:
a) tidal heating which melts and refreezes the surface
b) a collision which shattered it
c) plate tectonics (similar to Himalayan mountains)
d) flaws in the image
29) What is Neptune’s atmosphere mostly made out of?
a) methane
b) nitrogen
c) carbon dioxide
d) hydrogen
30) How is the energy that Neptune emits in the infrared generated?
a) absorbed from sunlight
b) winds
c) diamonds raining to the core
d) rotational energy
31) Triton is:
a) an original moon of Neptune
b) a captured Trans-Neptunian Object (TNO)
c) in a prograde orbit around Neptune
d) currently getting further away from Neptune
32) Why does Neptune have so few moons compared to the other gas giants?
a) it is too small to have a lot of moons
b) asteroid impacts have probably destroyed the other moons
c) because Triton tossed them out
d) Neptune tossed them all into the Oort cloud
Question 33 refers to the image below of Triton (moon of Neptune)
33) What do the dark splotches on the lower half of this image tell us about Triton?
a) Triton has an atmosphere
b) Triton has winds
c) Triton has volcanoes
d) all of the above
34) What is Triton’s fate?
a) Triton will probably be classified as a planet at the next IAU meeting
b) Triton will get ripped apart and create a spectacular ring system
c) Triton will escape from Neptune
d) Triton won’t do anything exciting
35) A lot of moons of the outer solar system have old and icy surfaces. What do they
look like?
a) very shiny (reflective) and heavily cratered
b) very shiny (reflective) and few craters
c) very dark and heavily cratered
d) very dark and few craters
36) How do we find Trans-Neptunian Objects (TNOs)?
a) they have a unique color
b) you watch for movement with respect to background stars
c) by looking for “wobbles” in Neptune’s orbit
d) you don’t find them, they find you
37) TNOs are the likely source of:
a) short period comets
b) long period comets
c) asteroids
d) shooting stars
38) Why is Pluto no longer considered a planet by the International Astronomical Union
(IAU)?
a) it is smaller than our moon
b) it is a member of a larger group of objects known as Plutinos
c) it is tidally locked to its largest moon
d) it shares a 3:2 orbital resonance with Neptune
e) all of the above
39) How many known moons does Pluto currently have?
a) 0
b) 1
c) 3
d) 5
40) Which of the following three statements is NOT true?
a) Pluto has a 3:2 resonance with Neptune
b) Pluto is not the largest TNO
c) Pluto is tidally locked to Charon
d) these are all true
41) All Plutinos have a 3:2 orbital resonance with Neptune. Most Plutinos at closest
approach to the sun are closer to the sun than Neptune is from the sun. Why is this a
stable orbit?
a) it isn’t
b) the expected collisional time with Neptune is 200 billion years
c) when Plutinos get to their closest point to the sun Neptune is 90 degrees away
in its orbit
d) Plutinos have tilted orbits such that they don’t actually cross the orbit of Neptune
(they go above or below it instead)
42) What is currently the largest known TNO?
a) Eris
b) Pluto (this answer is also acceptable within error bars)
c) Sedna
d) Quaoar
43) What are the densities of short period comet nuclei?
a) a quarter to half that of water
b) about 50% more than water
c) about two times that of water
d) about the density of air
44) Which of the following is NOT true of short period comets?
a) they tend to break apart
b) they have dark nuclei
c) their nuclei have young surfaces
d) if they survive they eventually run out of ices and become more asteroid-like
45) How far out from the sun does the Oort cloud go?
a) 1-2 light years
b) 1000 AU
c) 100 AU
d) 50 AU
46) If the USA were to switch its electricity from its current energy production methods
to mostly solar and wind, what would be the initial cost range of such a switch? Just
looking at electricity, not total energy.
a) $1-$10 billion
b) $50-500 billion
c) $1-$10 trillion
d) $90-900 trillion
47) Where do long period comets come from?
a) Kuiper Belt
b) asteroid belt
c) “Trojan” asteroids
d) Oort cloud
48) What % of USA’s total energy comes from fossil fuels (oil, natural gas, and coal)?
a) 10%
b) 25%
c) 50%
d) 85%
49) Which of the following is NOT a basic necessity for the most basic life as we know
it?
a) water
b) an atmosphere
c) Nitrogen
d) energy
50) If the distance from the sun to earth were to be scaled to 2 scale cm, then how far
away from the sun would Neptune be (actual orbital radius is 30 AU)?
a) 6 scale cm
b) 15 scale cm
c) 30 scale cm
d) 60 scale cm
51) Which of the following is the most accurate statement about the ancient Greeks
understanding of the circumference of the earth?
a) the ancient Greeks believed the earth was flat
b) some ancient Greeks thought the earth might be a sphere but were not able to
make any measurement as to its size
c) the ancient Greeks estimated the circumference of the earth to within 10% of
the actual value
d) many ancient Greeks thought the earth might be a sphere but the circumference
they estimated was far off of the actual value
52) Is Polaris (aka the North Star) the brightest star in the Northern hemisphere night
sky?
a) no
b) yes
c) Polaris is tied with another star for brightest
d) Polaris is not up at night
53) Which of the following was NOT an accomplishment of Tycho Brahe?
a) made measurements of Mars to an accuracy of 1 arc minute
b) proved that comets were not in the atmosphere
c) created a sun centered model of the solar system which was accepted by
scientists (although largely disregarded by everyone else)
d) Tycho accomplished all of the above
54) Which of these does Galileo NOT get credit for?
a) the first person to observe Neptune
b) the first person to document sun spots
c) the invention of the telescope
d) Galileo gets credit for all of these
55) What is Kepler’s first law?
a) orbits have no shape
b) orbits are elliptical
c) orbits are circular
d) orbits are triangular
56) Isaac Newton discovered:
a) that gravity creates a repulsive force which keeps everything away from the earth
and the sun
b) that gravity extends out far beyond the earth
c) that gravity only exists on the surface of an object
d) that apples fall faster than pears thus giving a relationship to the acceleration of
gravity to the mass of the object
57) Newton also discovered:
a) as 2 objects get further apart the force of gravity increases
b) there is no gravitational force once two objects are separated
c) as 2 objects get further apart the force of gravity is constant
d) as 2 objects get further apart the force of gravity drops
58) The corona of the sun is several million degrees. If a spacecraft could shield itself
from the rest of the sun, how would the corona affect the ship?
a) nothing
b) crush it
c) move it forward in time
d) fry it
59) Where on the sun could you land?
a) coronal hole
b) nowhere
c) core
d) bottom of the photosphere
60) We see emission lines when we look at the corona of the sun. What does this tell us
about the corona?
a) the corona is hot
b) the corona is “thin”
c) what the corona is made of
d) all of the above
61) You have a solid object at a cool temperature. What type of spectrum of light will
this cool object emit?
a) absorption
b) continuum
c) emission
d) none
62) “White” light is actually:
a) the result of diffracting a single color of light
b) a myth, there is not such thing as “white” light
c) a fundamental color of light
d) a combination of all of the colors of light
63) What causes the phases of the moon?
a) The rotation of the moon which makes the far side (aka “dark” side) face towards
the earth
b) The shadow of the earth.
c) Phases of the moon are random.
d) The moon’s orbit around earth combined with the part of the moon light by
the sun.
64) If the moon is 75 degrees from the sun (Elongation = 75 degrees) then what time of
the day will it rise?
a) 5 AM
b) 11 AM
c) 5 PM
d) 11 PM
65) During which phase of the moon do you get a solar eclipse?
a) 3rd quarter
b) full
c) 1st quarter
d) new
66) The highlands of the moon have far more craters than the Mare. What does this tell
you about the Mare?
a) The Mare were shielded from impacts.
b) The rocks in the Mare are younger than the rocks on the highlands.
c) The Mare are actually at higher elevations than the supposed “highlands”.
d) All of the above.
67) How many extinction events have there been in the history of the earth (according to
geological evidence)?
a) more than 2
b) 2
c) 1
d) 0
68) Tides are caused by:
a) winds
b) centrifugal force which results from the earth orbiting the sun at 30 km/s
c) the rapid rotation of the earth (much like a merry-go-round)
d) gravitational pull from the moon and sun
69) A probable explanation for Global warming is:
a) A term Politicians have come up with. All scientific evidence shows that global
warming does not exist.
b) Due to the strengthening of the greenhouse effect.
c) Due to the hole in the Ozone layer letting in more UV light from the sun.
d) Another term for the Greenhouse Effect.
70) What are the predicted worst case consequences of the current rate of change of
Carbon Dioxide levels in our atmosphere (assuming we do nothing to change it) in
the next 100 years or so?
a) Melting of ice caps.
b) Temperature rises of about 5K (10F).
c) Up to a 40 meter increase in sea levels.
d) All of the above.
71) Is there any liquid water on the surface of Venus?
a) no
b) yes
c) I am randomly guessing. Please give me a zero for this question.
d) I am copying off of my neighbor. Please give me a zero for the test.
72) What is the most influential reason for why the surface of Venus is extremely hot?
a) because of volcanoes
b) because the greenhouse dominated atmosphere is extremely thick
c) because Venus is 30% closer to the sun than the earth
d) because the atmosphere is 96% Carbon Dioxide
73) Which of the following is NOT a consequence of the freezing and thawing of Mars’s
ice caps?
a) creates global dust storms
b) the atmospheric pressure fluctuates greatly
c) makes the obit of Mars highly elliptical
d) these are all consequences
74) The resolution of a telescope is determined directly by:
a) its diameter
b) its collecting area
c) its magnification
d) how much light it collects
75) What is the order of the planets?
a) Mercury, Venus, Earth, Mars, Saturn, Jupiter, Uranus, Neptune
b) Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
c) Mercury, Venus, Earth, Mars, Jupiter, Saturn, Neptune, Uranus
d) Mercury, Venus, Mars, Earth, Jupiter, Saturn, Uranus, Neptune