AST 1010
Study Guide
Exam 1
Fall 2009
Sample short essay/math questions. I make no guarantee that any of these questions
will actually appear on the exam. They are given as examples of the types of questions
you may be given. You should also expect to see exam questions resembling questions in
the Lecture Tutorials.
1. Describe in detail the current scientific model of the arrangement of objects in the solar
system. Explain one piece of observational evidence to support this model.
2. Consider how astronomers gather data on celestial objects. Explain why the properties
of light are important to astronomers.
3. A radar pulse with a wavelength of 15.10 m is beamed at the planet Mars. The beam
returns 1012 seconds later. The measured wavelength of the return pulse is 15.12 m. Is
the planet Mars moving towards or away from the Earth at the time? How do you know?
4. A newly discovered asteroid is found to have an orbital period of 5.63 years. The
planet Mars has an orbital period of 1.8809 years. The largest asteroid, Ceres, has an
orbital period of 4.603 years. Does this new asteroid orbit nearer to Mars or nearer to
Ceres? Explain your answer.
5. Astronomers measure the spectrum of light coming to Earth from a distant star.
Explain how the astronomers might determine the chemical identity of the gases in the
star’s atmosphere.
6. Consider the four Jovian planets. There are noticeable bands of color in the
atmospheres of Jupiter and Saturn. Those of Uranus and Neptune are essentially a
featureless blue color. Explain these differences.
7. Use the nebular model for the formation of the solar system to explain the origin of the
observed differences in composition and structure between the inner four planets and the
next four, the so-called gas giants.
8. Describe the observed differences in the surfaces and atmospheres of the four terrestrial
planets.
9. The surface of Mars undergoes a seasonal variation in temperature similar to that
experienced on Earth. The surface of Venus does not experience such a seasonal
variation. Explain this observation based on your knowledge of the three planets.
10. Which objects of the solar system are considered the most likely places to find extraterrestrial life? Explain your answer.
11. There is talk of a plan to send astronauts to Mars. Choose one of the differences
between Mars and Earth and explain why that difference would make life difficult for the
astronauts while they are on Mars.
12. How long would it take for a radio signal transmitted by the Mars Explorer to reach
Earth if Mars is at its greatest distance? At its shortest distance? Assume that the signal
is transmitted from the side of Mars that is facing the Earth at the time of transmission.
13. Explain why the Moon goes through a series of phases. Be sure to include a
description of how the relative positions of the Sun, Moon and Earth affect this process.
14. Explain why most locations on the Earth experience a cycle of seasons. Be sure to be
specific as to which hemisphere you are describing.
15. Explain why a solar eclipse cannot be observed from anywhere on the surface of the
Earth each month.
16. The orbital period of an object in the Kuiper belt is 1085 years. Calculate the average
distance of this object from the Sun.
17. The average distance of Neptune from the Sun 30.0690 AU. Calculate the orbital
period of the planet Neptune.
18. Astronomers measure the light coming to Earth from a distant star. From this data
they can derives several types of spectra. Explain how the astronomers might use one of
these spectra to determine the star’s radial velocity relative to Earth.
19. Astronomers measure the light coming to Earth from a distant star. From this data
they can derives several types of spectra. Explain how the astronomers might use one of
these spectra to determine the temperature of the star’s photosphere.
20. Describe the differences between emission-line spectra and absorption-line spectra.
Using your knowledge of the structure of atom, describe how the interaction of light and
atoms produce each type of spectrum.
21. Describe the best current model of the origin of the solar system.
22. If humans ever build a permanent base on Mars spaceships will fly back and forth
carrying cargo and people. Will it require more energy, less energy or the same amount
of energy to lift a spaceship off the Earth than to lift the same ship off Mars? Explain
23. There are three reasons why the Moon’s surface has so many more craters than the
Earth’s surface. Explain all three.
24. List the eight planets in their usual order of distance from the Sun.
25. Which of these planets are classified as terrestrial? Which of these planets are
classified as Jovian?
26. Explain three differences that are observed between the terrestrial and the Jovian
planets. Don’t just list the differences; explain how the types of planet differ.
27. Humans have landed robot probes on the surfaces of Venus and Mars. Explain why it
would be impossible to land a probe on one of the Jovian planets.
28. When it is far from the Sun a comet is a dirty snowball. We observe certain changes
in the appearance of a comet as it moves nearer to the Sun. Describe why the changes
occur.
29. Mars has an average distance from the Sun of 1.52 AU. What is the maximum
distance that can exist between the Earth and the planet Mars? What is the minimum
distance that can exist between the Earth and the planet Mars? (Hint: what is the average
distance between the Earth and the Sun?)
30. The absorption spectrum of a certain star is recorded. An absorption line of hydrogen
is found at 745 nm in the spectrum of the star. In the lab this absorption line is found at
728 nm. Is the star moving towards or away from the Earth? Explain how you arrived at
this answer. Calculate the radial velocity of the star with respect to the Earth.
31. The spectrum of a star is recorded and a graph of intensity versus wavelength is
constructed. The peak of this graph is found at 567 nm. What is the temperature of the
star’s photosphere?
32. Suppose that an asteroid is discovered with an average distance from the Sun of 0.88
AU. What would be its period of revolution?
33. Suppose an asteroid with a period of revolution of 0.567 yr is discovered. What is the
average distance of this asteroid from the Sun?
34. Suppose that an asteroid is discovered with an average distance from the Sun of 5.88
AU. What would be its period of revolution?
35. Suppose an asteroid with a period of revolution of 11.5 yr is discovered. What is the
average distance of this asteroid from the Sun?
36. What is the temperature of a star whose dominant wavelength is 789.0 nm?
37. What is the dominant wavelength of a star with a photosphere temperature of 7900K?
38. The spectrum of a certain star is measured. An absorption line is noted at 655 nm in
the spectrum of the star. The same absorption line is found at 642 nm in a spectrum
measured in a laboratory. Is the star moving towards or away from the Earth? What is
the velocity of the stars motion towards or away from the Earth?
39. The spectrum of a certain star is measured. An absorption line is noted at 456 nm in
the spectrum of the star. The same absorption line is found at 468 nm in a spectrum
measured in a laboratory. Is the star moving towards or away from the Earth? What is
the velocity of the stars motion towards or away from the Earth?
40. Describe the best current model scientists have to explain the origin of the Moon.
EQUATIONS
Kepler's Third Law
P2 (yr) = a3 (AU)
wave equation
c = f
Doppler Effect
Volume of sphere
 = Vr
0
c
Distance Equation
d = vt
c = 2.998X105 km/s
V = 4 r
3
3
Newton's law of Gravity
F = Gm1m2
d2
Wien's Law
peak(nm) = 2,900,000
Energy of a photon
E = hc
λ
1 parsec = 3.26 ly
T(K)
Schwarzchild Radius
Rs = 3 Msun
h = 6.626X10-34 J·s