Astronomy 123
Test 1
April 27, 2017
NAME _______________________________________________________________

>Multiple Choice Questions -- 15 questions @ 2 points per question. Select the best answer for each question.
1. Astronomers pursue the study of stars and stellar evolution because _ .
a. stars are exceedingly powerful sources of energy
b. stars are intrinically interesting
c. stars may serve as high-energy physics laboratories
d. stars help us to understand how the Universe has evolved and how we came about in the Universe
e. All of the above were discussed in class as reasons which drive astronomers to study stars and stellar evolution.
2. Of the following parts of the electromagnetic spectrum, which pass freely through the atmosphere of the Earth?
a. x-rays and optical
b. radio and ultraviolet
c. radio and optical
d. ultraviolet and optical
e. infrared and gamma-rays

3. Two stars have the same surface temperatures but have different diameters. The larger star has a surface area 2 times greater than the smaller star. The luminosity of the larger star is how much larger than the smaller star?
a. 2 times as much
b. 4 times as much
c. 8 times as much
d. 16 times as much
e. 64 times as much

4. X-rays are _ than radio waves, _ radio waves.
a. more energetic -- and travel more quickly in vacuum than
b. more energetic -- but travel at the same speed in vacuum as
c. more energetic -- but, strangely, travel more slowly in vacuum than
d. less energetic -- but travel more quickly in vacuum than
e. less energetic -- and travel more slowly in vacuum than

5. The luminosity of the Sun _ the Solar Activity Cycle.
a. changes by less than 1 % over
b. doubles in size over
c. is 10 times larger around the maximum of
d. drops to 0 around the minimum of

6. The fundamental difference between radio waves and x-rays is that _ .

a. you can listen to radio waves
b. radio waves and x-rays always come from different sources
c. radio waves are wave-like while x-rays are particle-like
d. they travel at different speeds in a vacuum
e. they have different wavelengths

7. Stars and stellar systems have been studied .
a. through observations of their optical (visual) emission
b. through obsevations of their particle emissions
c. through observations of their gravitational radiation
d. Only A and B have used to study stars
e. A, B, and C have been used to stars and stellar systems

8. The colors of some glowing bodies are listed below. Which body is the coolest?

a. red
b. blue
c. yellow
d. green
e. purple

9. When the Sun first formed, it is thought to have been .

a. only 70 % as bright as it is today
b. about 30 % brighter that it is today
c. nearly three times brighter than it is today
d. about the same brightness it is today
e. nearly 10 times brighter than it is today

10. The Davis experiment designed to detect Solar neutrinos found that _ .

a. the number of neutrinos detected from the Sun was greater than predicted by theory
b. the number of neutrinos detected from the Sun was right on what was predicted by theory
c. the number of neutrinos detected from the Sun was less than what was predicted by theory
d. the number of neutrinos detected from the Sun oscillated; sometimes it was more than predicted by theory and sometimes it was less than predicted by theory

11. The most useful probe of the current state of the interior of the Sun _ .

a. is the Solar Wind, the high-speed stream of hydrogen emanating from the surface of the Sun
b. are the neutrinos from the Sun
c. is the radiation (the photons) we receive from the Sun
d. is the Solar Activity Cycle
e. are precise measurements of the Solar Constant

12. Astronomy is a difficult experimental science primarily because _.
a. stars are extremely distant
b. stars are very massive and are very rare
c. stars do not emit visible light and are thus unobservable with our eyes
d. stars are primarily composed of hydrogen and helium whereas oxygen is the most abundant element on the Earth
e. All of the aboe are the reasons astronomy is a difficult experimental science.

13. The Sun generates its energy output through _ .

a. processes similar to those utilized in coal burning plants on Earth
b. nuclear fusion of hydrogen to helium
c. harnessing of high-speed winds circulating just beneath the Sun's surface
d. a combination of fossil fuel burning and through slow contraction
e. fission reactors similar to those which currently generate power on the Earth
14. Elements important to life on Earth, such as carbon and oxygen, have their orgins in .

a. the violent events which started the expansion of the Universe 13.7 billion years ago.
b. the high-energy particle accelerators currently operating on the Earth
c. the cores of stars
d. the events which led to the formation of the planets themselves
e. collisions between our Universe and other universes early in the history of our Universe
15. What have we learned about neutrinos as a result of Solar Neutrino Experiments?
a. neutrinos are chamaleon-like objects in that they may change form as they travel through the Sun and then to the Earth
b. neutrinos are ghost-like particles that they may travel to other dimensions as they move through our Universe
c. neutrinos are actually not particles, they are a very long wavelength form of electromagnetic radiation
d. neutrinos are bad probes of the deep interior of the Sun because they take too long to diffuse from the center of the Sun to the surface of the Sun
e. neutrinos turned out to be an incorrect prediction made by particle physics theorists; neutrinos actually do not exist

Short Answer Questions -- 6 questions worth 35 total points. The questions are not weighted equally. Their point values are as indicated in the questions.

1. Solar-Terrestrial Connection [8 points]

a. Describe the Solar Activity Cycle.

b. What are the Maunder Minimum and the Dalton Minimum?

c. What observation (or Terrestrial events) show that the climate of the Earth is strongly affected by the activity of the Sun.

2. Binary Star Systems [5 points]

a. Astronomers have found that _______________________________ of the stars observed in the sky are in multiple star systems (binary systems, trinary systems, ... )
b. What stellar properties have been determined from observations of binary star systems?

3. Radiation Laws [8 points]

a. State Wien's Law.

b. State the Stefan-Boltzmann Law.

c. To what kind of object do the Wien Law and Stefan-Boltzmann Laws strictly apply? Why do astronomers find them such useful concepts?

4. Faint Young Sun Paradox [6 points]

a. How do we define the equilibrium temperature for a planet like the Earth?

b. Suppose the Earth did not have its current atmosphere, how would the estimate for the equilibrium temperature change?

c. Dsecribe the Faint Young Sun Paradox.

5. Electromagnetic Radiation [4 points]

a. As discussed in class, describe the nature of electromagnetic radiation.

b. List the types of electromagnetic radiation in order of decreasing wavelength.

6. Celsius, Farenheit, Centigrade, and Kelvin [4 points]

a. As discussed in class, what is meant by temperature?

b. What is meant by absolute zero? What temperature scale is most commonly used by astronomers and other scientists?

Part
Points

Multiple Choice

Short Answer

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