Solar System Astronomy 29:52
Fall 2004
Exam 4 key (
This is
a closed book exam. Choose the one alternative that best completes the
statement or answers the question.
1) Which statement is incorrect concerning the
asteroid Ceres?
A) It was discovered by an Italian priest
B) It is the largest known asteroid
C) the mass
of Ceres is more than half that of the Earth’s Moon
D) Ceres is a member of the main asteroid belt
E) It was discovered
more than 200 years ago
2) Which of the following is thought to be
responsible for the
A) Perturbation by Uranus
B)
Perturbation by Jupiter
C) Sheparding asteroids near the
gaps
D) Gravitational pull of Mimas
E) Effect of Kuiper belt comets on the orbits of asteroids
3) A C-type asteroid has a ___ albedo and
comprises ___ of all asteroids
A) low, about 75%
B) high, about 10%
C) low, less than 1%
D) high, about 50%
E) high, less than 1%
4) Which statement is incorrect concerning
spacecraft exploration of asteroids?
A) the spacecraft Galileo
discovered an asteroid with a ‘moonlet’
B) a spacecraft (NEAR) landed on an
asteroid and took pictures of the surface
C) spacecraft pictures of asteroids
show surfaces with many small craters
D) the shape of asteroids in
close-up pictures is irregular (not spherical)
E) spacecraft have
detected liquid water on two large asteroids so far
5) Which observation is not relevant to the
‘killer asteroid’ theory of the extinction of dinosaurs?
A) Existence
of large-scale magnetic disturbances in fossils.
B) Abrupt increase in iridium abundance in rock layer at KT
boundary.
C) Discovery of large 100 km crater in
D) Evidence for period mass extinctions on ~100 Myr timescale
E) Existence of NEO families with Earth-crossing orbits.
6) The asteroid though to be responsible for the
mass extinction in 65 Myr BCE had a size near
A) 100 m
B) 10 km
C) 100 km
D) 1,000 km
E) size of the Moon
7) ‘Hydrostatic equilibrium’ in solar physics means
a balance between _____ and _____.
A) gravity, magnetic pressure
B) tidal forces, frozen water
pressure.
C) gravity, gas pressure
D) solar flare pressure, coronal
pressure.
E) radiative zone force, convective
zone force
8) In the Sun’s interior, energy is transported
by what means?
A) radiation
B) convection
C) both radiation and convection
D) gravity
E) gravity and conduction
9) In the core of the Sun, which statement is not
correct?
A) temperature is about 15 million
K
B) hydrogen is converted to helium
C) gamma rays are created
D) neutrinos are created
E) helium is converted to carbon
10) The
luminosity of the Sun is 4·1026 W (1 Watt= 1 Joule/sec). How much
mass is being converted to energy by fusion in the Sun every second?
A) 1.2·104 kg
B) 4.4·109
kg
C) 4.4·1012 kg
D) 1.3·1018 kg
E) 4.0·1026 kg
11) What is the primary source of energy in the
core of the Sun?
A) heat
B) light
C) x-rays
D) gamma rays
E) neutrinos
12) The mass of a helium (He4) nucleus
is:
A) a little more than 4x the mass
of a hydrogen nucleus
B) exactly 4x the mass of a
hydrogen nucleus
C) a little less than 4x the mass of a hydrogen nucleus
D) exactly 2x the mass of a
hydrogen nucleus
E) more than 10x the mass of a
hydrogen nucleus
13) Why do meteors from a given meteor shower
always originate from a specific direction in the sky (the radiant)?
A) The comet causing them is located in that direction
B) The particles are bursting from a large disintegrating object
in that direction
C) The particles are ‘falling’ from a certain direction in
the upper atmosphere
D) This is
caused by the Earth’s direction of motion when it intercepts the comet’s orbit
E) This isn’t true (old wives’ tale). Meteors originate
randomly from all directions
14) What happens to neutrinos in the solar
interior?
A) they combine with hydrogen to
form deuterium
B) they collide with atoms and lose
energy
C) they scatter and heat the
surrounding gas
D) they are absorbed by atoms of
helium and carbon
E) nothing, they leave with no significant interaction
15) Why do sunspots appear dark?
A) They are quite cold (about 300°K)
B) They contain significant abundance of sooty carbon
C) They are concentrations of low albedo materials
D) The ‘fire’ in their core has been extinguished by dense
materials
E) they are somewhat cooler than their surroundings, and less
bright by contrast
16) The year 2001 was a peak in the observed
number of sunspots. When can we expect the next peak?
A) 2006
B) 2012
C) 2023
D) 2101
E) Can’t predict: sunspot activity is completely unpredictable.
17) Why are solar
neutrino telescopes located in deep mines?
A) they are very sensitive to
external light.
B) they must be isolated from
surface vibrations.
C) they must be in a sterile,
oxygen free environment
D) they need to be protected from
direct sunlight
E) the soil above the detectors filters out cosmic rays.
18) Which component of the solar atmosphere is
the hottest?
A) photosphere
B) chromosphere
C) corona
D) top of the convection zone
E) ionosphere
19) Which statement is not correct regarding the
‘solar neutrino’ problem? [Note! question had 2 correct answers – your
will receive credit for either D or E]
A) Neutrino telescope in S.D. measured 1/3 the expected
number of solar neutrinos
B) The ‘missing neutrino’ problem was recently solved using
a detector in
C) neutrinos can transform into one
of three ‘flavors’: electron, muon, tau
D) the solution to missing solar neutrinos was that neutrinos
are absorbed in the solar interior
E) The
‘solar neutrino’ problem remains one of the unsolved mysteries in astrophysics.
20) Which global climate change on Earth is
coincident with an observed decrease in solar activity (sunspots)?
A) Medieval Warm Period (1000AD - 1350AD)
B) Little
Ice Age (1680AD - 1750AD)
C) Hottest decade ever recorded (1990AD - 2000AD)
D) End of last glaciation (12000
BCE
E) all of the above
21) The size of a large sunspot group is about:
A) 100 km
B) ‘the size of
C) the size of the Earth (10,000
km)
D) 5x-10x
times the size of the Earth (50,000 - 100,000 km)
D) about ½ the diameter of the Sun
(1,000,000 km)
E) large sunspot groups cover the
entire circumference of the Sun
22) Why is the simple description of
proton-proton fusion: ‘four hydrogen
atoms collide to form a single helium nucleus’ incorrect?
A) the end product is deuterium,
not helium
B) fusion happens when gamma rays annihilate
C) hydrogen cannot form helium! – all elements are immutable
D) the probability of 4 hydrogen nuclei simultaneously
colliding is essentially zero
E) the
helium nucleus that is formed isn’t single: it breaks into 2 pieces
23) If the Sun could use all of its hydrogen in a
fusion process, how many years could it shine at its present luminosity?
A) 4.5 billion
B) 9 billion
C) 90
billion
D) 5 trillion
E) 9 gazillion
24) Gamma ray photons which are created in the
core of the Sun take ____ to escape from the surface, at which time, they are
primarily_____
A) a
few seconds, neutrinos
B) a few minutes, x-rays
C) a
week, still gamma rays
D) about 100,000 years, visible photons
E) a
few million years, heat waves
25) Why don’t CME (coronal mass ejection)
particles cause aurorae over the entire Earth?
A) CME’s don’t ever hit the Earth
– they cannot travel that far
B) CME’s don’t have energetic
particles that cause aurorae
C) the CME events only occur in
directions away from the ecliptic plane
D) the Earth’s magnetic field deflects the particles toward the
polar regions
E) They actually do, but we don’t see them since it’s daytime then (observer on Earth is on Sunlit side)
Equations
1. Mass-energy equation
where E
= Energy produced by conversion of mass (Joules), m = mass converted to energy (kg), c = speed of light (3·108 m/sec).
Example: A typical car traveling on the
highway requires about 100,000 (105) Joules/sec to operate. How much
mass would need to be converted to energy to operate the car continuously
for ten years?
Answer: 10 years is 3600·24·365·10 = 3.2·108
seconds, so the total energy required is:
Solve for mass (m) required:
