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Spring 2002 Final Exam
MULTIPLE CHOICE QUESTIONS (100 pts.)
USING WHAT YOU HAVE LEARNED IN ASTR 101, PLEASE CHOOSE THE BEST
ANSWER TO EACH OF THE FOLLOWING QUESTIONS AND INDICATE YOUR CHOICE
ON THE SCANTRON SHEET. (2 pts. each)
1. In the Greek geocentric model, epicycles were used to explain
A. retrograde motion.
B. the equinoxes.
C. eclipses.
D. lunar phases.
E. precession.
2. During the crescent phase of the Moon, earthshine is easily visible. This results from
A. the use of too much moonshine.
B. refraction of sunlight by the moon's atmosphere.
C. reflection of sunlight off the Earth, then off the Moon.
D. infrared emission by the Moon.
E. infrared absorption by the Moon.
3. Spectroscopic binaries are recognized by
A. observing the stars as double images through a powerful telescope.
B. the eclipses that always occur.
C. changing spectral line positions due to the Doppler shift as the stars orbit.
D. spectral lines that change from emission to absorption.
E. changing spectra that indicate a hotter then a cooler body.
4. A primary use of 21 cm radiation is to determine
A. distances to distant stars.
B. the chemical composition of the interstellar medium.
C. the distance to the Andromeda galaxy.
D. the spiral structure of our Milky Way galaxy.
E. the magnetic field of the Milky Way galaxy.
5. Which of the following is true of a K5 red giant and a K5 main sequence star? They have the
same
A. luminosity.
B. mass.
C. surface temperature.
D. size.
E. age.
6. There is evidence in the rock record that oxygen began to be prevalent about 2 billion years
ago. It is assumed that ozone began to build up in the stratosphere at this time also
A. making it possible for life to survive on the land.
B. and the greenhouse effect resulted.
C. creating an ozone hole over the south pole.
D. as carbonate rocks formed.
E. as limestones began to form.
7. For a one solar mass star, which of the following is the correct order for its evolution?
A. protostar, planetary nebula, main sequence, red giant, white dwarf
B. protostar, main sequence, planetary nebula, red giant, white dwarf
C. protostar, main sequence, red giant, planetary nebula, white dwarf
D. planetary nebula, protostar, main sequence, red giant, white dwarf
E. planetary nebula, protostar, main sequence, supernova, black hole
8. The HR Diagram is a graph that relates
A. period and luminosity.
B. temperature and mass.
C. color and temperature.
D. apparent magnitude and luminosity.
E. spectral type and absolute magnitude.
9. In the last lab (using the computers) dealing with the expansion of the Universe, you used
Hubble’s constant to estimate
A. the velocity of recession.
B. the Gravitational constant.
C. distance to a Cepheid variable.
D. the age of the Universe.
E. the mass of a galaxy.
10. Life on Earth depends strongly on which atom that forms long chains with itself leading to
complex molecules?
A. oxygen
B. hydrogen
C. carbon
D. nitrogen
E. iron
11. As a ground state electron in a hydrogen atom changes its spin direction
A. the atom is ionized.
B. a photon of wavelength 21 cm is emitted.
C. a long wavelength infrared photon is absorbed.
D. the atom becomes helium.
E. the atom is no longer considered to be radioactive.
12. The Voyager I space probe has reached the speed necessary to escape from the Sun's gravity.
It currently is 10 billion miles from Earth. Its engine suddenly malfunctions and is no longer
operational. What would happen next to Voyager I?
A. It will stop immediately.
B. It will slow down and quickly come to a stop.
C. It will slow down and be pulled back toward the Sun.
D. It will continue to move at the same speed in a straight line.
E. It will continue to move but be drawn into a large elliptical orbit around the Sun.
13. The Sun is located ____________galactic center.
A. about 3,000 light years from
B. in a globular cluster about 300,000 light years from
C. very near
D. in a spiral arm about 30,000 light years from
E. at the outer edge of the galaxy 100,000 light years from
14. You are at the beach (east coast) this summer and can't sleep, so you go outside. Over the
ocean in the east you see a crescent moon with earthshine. Estimate the time.
A. 8 pm
B. 10 pm
C. midnight
D. 2 am
E. 4 am
15. We do NOT experience a lunar eclipse once a month because
A. the Moon's orbit is inclined at 5o to Earth's orbit.
B. the Moon does not rotate.
C. the Moon does not revolve.
D. the Moon's rotational and revolutionary periods are equal.
E. one lunar side always faces the Sun.
16. Cepheid variables can be used to determine distance because a Cepheid's
A. radial velocity is related to its mass.
B. luminosity is related to its period of variation.
C. size is related to its mass.
D. magnitude is related to its color.
E. period of variation is related to its velocity of recession.
17. Before the Apollo landings on the Moon, the lunar maria were hypothesized to be younger
than the highland regions because they
A. are lighter in color.
B. are darker in color.
C. have more craters.
D. have fewer craters.
E. were formed by flowing water.
18. Suddenly you and your friend see a bright light streak across the sky on a clear evening. Your
friend yells, "Look at the falling star." You tell him that you have just witnessed
A. a comet crossing the sky.
B. a strange form of heat lightning.
C. a piece of interplanetary debris burning in the atmosphere.
D. a piece of matter shot out of a star.
E. an aurora.
19. The Sun's true position in our galaxy was first determined using
A. pulsars.
B. open clusters.
C. globular clusters.
D. giant molecular clouds.
E. clusters of galaxies.
20. The Big Bang theory received its strongest observational support with the detection of
A. 21 cm radiation.
B. quasars.
C. the cosmic background radiation.
D. open clusters.
E. objects like Cygnus X-1.
21. If all of the gases trapped in shells and carbonate rocks were released, the Earth's atmosphere
would be more like the atmosphere of
A. Jupiter.
B. Mars.
C. the Moon.
D. Titan.
E. Venus.
22. The source of the Sun’s energy is
A. chemical burning of hydrogen gas.
B. gravitational heating.
C. fission of nuclei.
D. hydrogen fusion.
E. tidal stresses from the planets.
23. Your latitude right now on Earth is the altitude of
A. the ecliptic.
B. your zenith.
C. the horizon.
D. the North Celestial Pole.
E. the celestial equator.
24. If the Moon rises at sunrise, what is its phase?
A. new
B. full
C. first quarter
D. last quarter
E. gibbous
25. If the universe is comprised of more than 90% dark matter, then in the future
A. the universe will experience the Big Crunch.
B. the universe will expand forever.
C. new galaxies will continue to form forever.
D. galaxies will soon darken as star formation ceases.
E. supermassive black holes will gradually devour their host galaxies.
26. Why does heliocentric parallax only work as a reliable distance method for relatively nearby
stars?
A. Spectra can only be taken for the brightest stars that are relatively nearby.
B. As distance increases, the parallax angle becomes too small to measure accurately.
C. It takes centuries to determine accurate parallaxes and astronomers have only had
powerful telescopes recently.
D. The mathematics becomes more difficult for other stars.
E. This method only works for stars that are circumpolar.
27. The various forms of electromagnetic radiation are distinguished from one another by
differing
A. wavelengths.
B. photon energies.
C. velocities.
D. all of the above.
E. only answers A and B
28. Most of the stars in our galaxy (about 90%) are classified as main sequence stars on the HR
Diagram. This is because
A. it is the only stable configuration for a star.
B. there are no old stars in our galaxy.
C. it is the longest lived phase of evolution for most stars.
D. red giants only form from the relatively rare high mass stars.
E. there are no stars younger than the Sun in our galaxy.
29. If the mass of a supermassive black hole is 10 million solar masses, what is the radius of its
event horizon?
A. 10 million km
B. 30 million km
C. 100 million km
D. 300 million km
E. 900 million km
30. A growing number of extrasolar planets have been detected since 1995 using
A. the Hubble Space Telescope.
B. the VLA (Very Large Array of radio telescopes).
C. detailed spectra of stars that show a small regular change in Doppler shift.
D. the 200 inch telescope to make very long exposures.
E. the Voyager spacecraft, which now orbit galactic center
31. If humans do make contact with an intelligent extraterrestrial civilization in another star
system using radio telescopes, which of the following is most likely to be true?
A. The civilization will be very primitive compared to us.
B. We will not be able to understand their message since they will have a different
language.
C. Two way communication will take many years to complete.
D. Their laws of chemistry and physics are likely to be radically different from ours.
E. They will look like Mr. Spock.
32. Which of the following lists is correctly arranged in order of increasing radius?
A. comet nucleus, the Moon, a white dwarf, Jupiter, the Sun
B. the Moon, comet nucleus, Jupiter, a white dwarf, the Sun
C. a white dwarf, comet nucleus, the Moon, Jupiter, the Sun
D. the Moon, Jupiter, a white dwarf, the Sun, comet nucleus
E. none of the above
33. Comparing our planet to the rest of the Terrestrial planets in our Solar System, which
property is unique to the Earth?
A. volcanic activity occurring at some time during history
B. liquid water on surface for nearly entire history
C. polar ice caps
D. a solid surface
E. a greenhouse effect
34. From the list below which body would be hottest right now on the surface facing the Sun?
A. Mercury
B. Venus
C. the Moon
D. Earth
E. Mars
35. In class, the mass extinctions that included the dinosaurs was linked to an astronomical event.
This event was
A. a collision between the forming Earth and the Moon.
B. a collision between the Earth and a black hole.
C. a flood caused by melting polar caps.
D. a collision between the Earth and an asteroid.
E. big game hunting by extraterrestrials.
36. The single most important factor influencing a star’s evolution is
A. the strength of its magnetic field.
B. its rotation rate.
C. its mass.
D. its location in the galaxy.
E. its surface temperature.
37. Both the largest and the smallest galaxies are classified as
A. normal spirals.
B. barred spirals.
C. quasars.
D. pulsars.
E. ellipticals.
38. Galileo's telescopic observations provided support for the
A. Big Bang theory.
B. protoplanet theory.
C. geocentric theory.
D. heliocentric theory.
E. theory of general relativity.
39. A spiral galaxy is recognized in the Ursa Major Cluster. It is 1/4 the angular size of a spiral
galaxy in the Virgo Cluster when viewed through the same telescope. Assuming that these spiral
galaxies are similar in true size, what can astronomers say about the distance to the Ursa Major
Cluster?
A. It is about 4 times closer than the Virgo cluster.
B. It is about 4 times farther than the Virgo cluster.
C. It is at the same distance as the Virgo cluster.
D. It is about 16 times closer than the Virgo cluster.
E. It is about 16 times farther than the Virgo cluster.
40. The statement that astronauts are weightless on the Moon is
A. true, because they are in a vacuum.
B. true, because there is no gravitational force on them when they are on the Moon.
C. true, because they must wear spacesuits.
D. false, because they wear special magnetic shoes to hold them on the Moon.
E. false, because the Moon exerts a gravitational force on their bodies.
41. Of the planets visible during this semester in the west after sunset, which has been the
brightest?
A. Venus
B. Jupiter
C. Mars
D. Saturn
E. Mercury
42. When satellite telescopes discovered strong X ray sources in the sky, astronomers knew that
the X rays weren't coming from ordinary stars because
A. stars are not hot enough to emit many X rays.
B. stars are too hot to emit many X rays.
C. X rays can only be produced in explosions.
D. stars do not rotate fast enough to produce X rays.
E. stars are not red shifted enough to produce X rays.
43. Astronomers have recently discovered some pairs of quasars that appear close to each other
and that have identical red shifts. The current explanation for this observation is
A. matter-antimatter annihilation.
B. two quasars orbiting around each other.
C. telescopic distortion.
D. gravitational lensing by an intervening massive galaxy.
E. a black hole in a binary system.
44. From Earth we see the same side of the Moon (the "man in the moon face") because
A. the Moon does not rotate.
B. the Moon's orbit is inclined to the ecliptic.
C. the Moon rotates once per revolution.
D. sunlight never hits the farside.
E. Earthshine only hits the side that we see.
45. If a scale model of the Solar System were constructed on the Byrd Stadium football field here
at the University of Maryland, where would the closest star (other than the Sun) be located?
A. at Baltimore harbor
B. in Los Angeles, CA
C. in Boston, MA
D. somewhere in China
E. near the Moon
46. Planets near the Sun are composed of mostly rock and iron. How does Solar System
formation theory account for this?
A. The Sun’s magnetic field attracted all of the iron in the nebula toward the inner Solar
System.
B. The forming Sun’s heat prevented other substances such as ices to condense near it.
C. The planets that today are far from the Sun were captured.
D. The planets that today are near the Sun were captured.
E. All of the planets were captured, so the densest ones are closest to the Sun due to
gravity.
47. How were the five naked eye planets noticed and recognized by ancient astronomers?
A. These planets are the five brightest objects in the night sky.
B. Planets are observed to “twinkle.”
C. Planets were observed to move with respect to the stars.
D. The epicycle of each planet is easily visible.
E. These planets always were observed to lie on the celestial equator.
48. The mass of Jupiter was first calculated
A. from analysis of the motions of its moons.
B. using its distance from the Sun and its rotational period.
C. using its angular size and distance from Earth.
D. using data from spacecraft flybys.
E. by measuring the time that it takes for the Red Spot to disappear from view.
49. If you were thrown onto the Martian surface near the equator without a spacesuit, what
would be the most likely cause of your death?
A. Volcanic activity would bury you under a layer of sulfur.
B. You would slowly freeze to death.
C. You would suffocate and have problems dealing with the low atmospheric pressure.
D. You would be crushed by the high atmospheric pressure.
E. Hungry Martian microbes would eat you.
50. For the diagram below which spectrum would you observe?
Diagram given in Discussion Section
A. continuous
B. absorption
C. emission
D. blue shifted
E. red shifted
SHORT ANSWER QUESTIONS (50 pts.)
PLEASE ANSWER THE FOLLOWING QUESTIONS AS COMPLETELY AS YOU CAN
USING WHAT YOU HAVE LEARNED IN ASTRONOMY 101.
51. a) How do astronomers explain a pulsar’s radio wave variations? Include a labeled sketch.
(4 pts.)
b) Describe the cosmic background radiation. (4 pts.)
c) Why can't astronomers see photons emitted any earlier than from the time the cosmic
background radiation was produced? (2 pts.)
52. Hubble was the first astronomer to effectively study galaxies.
a) What advancement made it possible for Hubble to make his discoveries? (2 pts.)
b) How did Hubble first establish that the Andromeda spiral nebula was not part of the Milky
Way, but a separate galaxy? Be sure to state which observations had to be made and analysis
done in order to make this discovery. (4 pts.)
c) Hubble is given credit for having discovered the expansion of the universe. What do
astronomers mean when they say that “the universe is expanding?” Discuss Hubble’s
observations that led to the conclusion that the universe is expanding. (5 pts.)
53. a) How are galaxies arranged in space? Describe mapping methods and results. (5 pts.)
b) Why can't the center of the Milky Way be photographed with an optical telescope (using
visible light)? Explain. (3 pts.)
EXTRA CREDIT (2 pts. maximum) What is Einstein's Cross? Explain.
EXTRA CREDIT (2 pts. maximum)
This summer the Perseid meteor shower will occur on August 12. Describe what happens during
this event and give its cause.
54. a) Astronomers suspect that Cygnus X-1 is a black hole. Explain why. (4 pts.)
b) Black holes have been observed in nearby galaxies. How do they differ from the Cygnus
X-1 black hole? (2 pts.)
c) Describe the model that has been developed to explain the observations made of quasars.
Include a labeled sketch that accounts for their tremendous luminosity and the production of X
rays. (5 pts.)
55. a) Using what you know about stars and stellar evolution which stars would make the best
candidates to have planets with intelligent life forms? Choose 2 kinds of stars and justify. (4 pts.)
b) Choose an example from ASTR 101 that illustrates the process of obtaining knowledge using
the scientific method. Explain in a paragraph how your example shows how the scientific
method operates. (6 pts.)
EXTRA CREDIT (2 pts.)
The Andromeda galaxy is referred to as "M 31." What does “M 31” represent? Explain.