Download Sample exam 2

Astronomy 100
Sample exam 2 (Chapter 5 through 7)
Open book, exercises, handouts and notes, no collaboration. You have 50 minutes.
Short answer — answer all questions
1. Give a full bibliographic citation of one of the references you will be using on your
poster. At a minimum, the citation should contain the names of the author(s), the title of
the work or URL, and the publication date.
2. In the figure below, the four numbered arrows show electrons in a hydrogen atom
transitioning between their “allowed” energy levels. Circle the one(s) that will result in
a hydrogen photon emission.
3. State “absorption” or “emission” for the best type of spectrum to find out the
information requested:
a. The identity of various atmospheric gases on Titan
b. The identity of various hot gases in the Orion Nebula
4, Order the creation of the following bodies in the solar system, from oldest (1) to
youngest (4):
a. Planetesimals
b. Chondrules
c. Planets
d. Solar nebula
5. Match the planet described with an appropriate surface characteristic.
Terrestrial planet with much internal heat
Have more methane than helium
Jovian planet bigger than Jupiter
Emits more energy than it receives
Jovian planet smaller than Jupiter
Huge number of impact craters
Terrestrial planet with little to no internal heat
Active volcanism and/or tectonics
6. Which of the following features of a telescope would lead to better magnification?
Circle all correct answers.
A longer focal length objective
A shorter wavelength photon detection
A larger diameter objective
A shorter focal length objective
A longer focal length eyepiece lens
A longer wavelength photon detection
A smaller diameter objective
A shorter focal length eyepiece lens
7. a. Name a body in the solar system from which we could obtain pristine (original)
rocky solar nebula material.
b. Name a body in the solar system from which we could obtain pristine (original) icy
solar nebula material.
8. Match the equation with its appropriate use:
€
λ
− λlab
v
= shift
c
λlab
The temperature of the Sun
P2 = a3
The indirect detection of an extrasolar planet
T=
€
€
3 × 106
λ
&λ)
θ ≈ 250, 000 × ( +
' D*
How well can my telescope “see”?
The orbital period of a particle in the Cassini Division
9. What mechanism is most responsible for generating the internal heat of Io that
drives its volcanic activity? (choose one)
a. tidal heating
d. differentiation
b. bombardment
c. radioactive decay
e. accretion
10. Which of the following phenomena are attributable to orbital resonance? (choose
all that apply)
a. The Cassini Division in Saturn’s rings
b. The high wind speeds of Neptune’s atmosphere
c. The Kirkwood gaps in the asteroid belt
d. The orbital periods of Jupiter’s Gallilean satellites
Essay questions — choose two of the following questions; circle the numbers of the
ones chosen, so I know which ones to grade. Please answer each question in
sentence/paragraph format or a drawing, depending on what is asked.
11. Venus, unlike Earth, has almost no planetary magnetic field; the reason that is
given in the text is that Venus’s rotation is quite slow compared to Earth. As you are
reading this, one of your classmates (the annoying one) says, “No way! Venus doesn’t
have a magnetic field because it doesn’t have an iron core.” Before you can say anything,
another classmate (the other annoying one) says, “You’re wrong! Venus has an iron core
but none of it is liquid.” Explain, with great satisfaction, how both of them are wrong –
address the substance of their comments, and don’t just say “the book said so.” Hint:
Should Venus and Earth have had such different formation histories?
12. The rotational rate of Venus is really hard to determine, because Venus’s surface
features cannot be seen under its thick opaque atmosphere. But it was known long
before any spacecraft came anywhere near it! In fact, radar (radio waves) beamed
from Earth at Venus and the Doppler shift were used in 1961 to determine Venus’s
rotational rate of 243 Earth days. Describe how Earth-based radio waves aimed at Venus
and the Doppler shift could be used to figure out Venus’s rotational rate/
13. Would it be reasonable for a Sun-size star to have one terrestrial planet (mass and
diameter similar to Earth) orbiting at a = 7 AU, and no other planets? Explain your
answer, using the current ideas about how solar systems form.
14. Answer both parts: a. The small moon Amalthea orbits Jupiter at about the same
distance in kilometers at which Mimas orbits Saturn, yet Mimas takes almost twice as
long to orbit. From this observation, what can you conclude about how Jupiter and
Saturn differ? Be as quantitative as you can.
b. Jupiter and Saturn are not very different in radius. When you combine this
information with your answer to the previous part, what can you conclude about the two
planets? Again be as quantitative as you can.