NAME __________________________________ LAB # ____________________
Astronomy 1001 - Midterm #2 - April 6th Dr. Robert Gehrz- Spring 2005
Read Instructions Carefully:
1. MARK THE ANSWERS YOU CHOOSE ON THIS TEST AS IT IS YOUR ONLY
OPPORTUNITY TO CHECK WHICH ANSWERS YOU GOT RIGHT OR WRONG.
This will not be done for you at a later time in the departmental office. Exams will be returned
in lab; be sure to include your LAB section number on each page where indicated.
Without your lab NUMBER, the return of your exam will be delayed as well as the
posting of your score.
2. Print your NAME, ID # and SECTION # on the bubble sheet where appropriate. Your
SECTION # should read 02. All three items are necessary for the proper scoring and
computer transfer of your scores.
3. Use a pencil, make your marks dark and neat, and erase thoroughly.
4. There is only one answer to each question. Choose the best answer.
5. You may use this test for scratch paper.
6. One page (two sides) of notes is allowed for the exam.
Part I. Multiple Choice (3.2 pts. each)
1. Cooler, less luminous main sequence stars have
a. higher masses.
b. lower masses.
c. the same masses as hotter stars
d. masses that vary widely
2. Main sequence stars with the largest mass would be found where on the H-R diagram?
a. upper left b. lower left c. upper right d. lower right
3. Two important characteristics of sunspots are:
a. low temperature and intense magnetic fields
b. high temperature and intense magnetic fields
c. high temperature and weak magnetic fields
d. low temperature and no magnetic fields
4. The chemical composition of Jupiter and Saturn indicates the two most abundant elements in these planets are:
a. silicon and carbon
b. silicon and oxygen
c. hydrogen and helium
d. hydrogen and oxygen
5. Which of the following do the rings of Jupiter, Saturn, and Uranus have in common?
a. Small particles orbiting the planet
b. Solid sheets of icy materials
c. Made of dark, uncoated rocky particles
d. Made of light-colored, metallic particles
6. Which of the following is NOT a correctly stated key fact about the solar system that any model of its origin must explain?
a. The planets roughly lie in the same plane
b. The planets revolve about the sun in the same direction
c. The sun contains most of the solar system's mass
d. The sun spins faster than do the planets
7. In order to find the earth-sun distance in units such as kilometers, we:
a. bounce radar signals off the sun
b. bounce radar signals off the moon
c. bounce radar signals off Venus
d. know the light travel time from the sun to the earth
8. The two most abundant solar elements, in terms of its mass, are:
a. carbon and oxygen b. helium and carbon c. hydrogen and oxygen d. hydrogen and helium
9. An object that is red-shifted is
a. red in color
b. moving away from us
c. moving toward us
d. more than one answer is correct
10. To determine a star's distance, astronomers watch a star's position shift as the Earth moves from one side of the Sun to the other. If a star is closer, its parallax will be __ than for farther stars.
a. larger
b. smaller
c. the same
d. This is a trick question. Stars do not move at all!
11. Ninety percent of stars in the Hertzsprung-Russell Diagram are
a. white dwarfs b. on the main sequence c. red giants d. binary stars
12. What is inferred to be the source of the sun's energy right now?
a. Fusion of hydrogen to helium in the core
b. Gravitational energy released by collapse
c. Fission reactions in the core
d. Chemical oxidation (burning) of materials such as carbon
13. The primary transport system for heat to get from the core of our Sun to its surface, as evidenced by its "granular appearance" is:
a. radiation b. conduction c. convection d. levitation
14. Which characteristic of a star determines all other its other characteristics and its evolution?
a. distance b. luminosity c. temperature d. mass
15. What are the satellites of the outer planets thought to be composed of?
a. Hydrogen and helium
b. Hydrogen and methane
c. Water and carbon dioxide
d. Ice and rock
16. The composition of stars is determined by analyzing
a. Doppler shifts b. brightness c. absorption spectra d. radius
17. The Sun is supported against the crushing force of its own gravity by:
a. magnetic forces b. its rapid rotation c. gas pressure d. all of the above
18. An eclipsing binary star like Algol is a pair of stars that orbit around each other with the plane of the orbit oriented so that an observer on Earth can actually see the stars cross in front of one another. From this orbital motion, one can directly measure the stars':
a. radii b. luminosities c. masses d. distances e. a and c
19. The infrared spectra for comet comae and tails shows that they contain:
a. mainly water
b. tiny dust grains that are the building blocks of the planets
c. nothing that is recognizable
d. mainly hydrogen gas
20. We measure the temperature of the Sun and other stars by
a. sending a graduate student with a thermometer to measure them
b. plotting them on the H-R diagram
c. analyzing the peak wavelength of the light that they emit
d. analyzing the amount of light received by Earth
21. Comets and asteroids are likely
a. some of the oldest objects in our Solar System
b. some of the most newly formed objects in our Solar System
c. are a mixture of new and old objects
d. none of the above; we have no way to determine their age
22. The force that pulls an interstellar cloud together as it rotates is
a. gravity b. magnetism c. electricity d. friction
23. What is the difference between emission and absorption in terms of what happens to an electron in an atom?
a. In emission, the atom's nucleus goes from a lower to a higher orbit; in absorption, the nucleus goes from a higher to a lower orbit.
b. In emission, the atom's nucleus goes from a higher to a lower orbit; in absorption, the nucleus goes from a lower to a higher orbit.
c. In emission, the electron goes from a lower to a higher orbit; in absorption, the electron goes from a higher to a lower orbit.
d. In emission, the electron goes from a higher to a lower orbit; in absorption, the electron goes from a lower to a higher orbit.
24. Jupiter has a relatively strong magnetic field which has been measured by planetary probes. The physical explanation is that Jupiter's:
a. core is made of metallic hydrogen and the planet rotates rapidly
b. core is made of metallic hydrogen and the planet rotates slowly
c. core is made of molten iron and the planet rotates rapidly
d. core is made of molten iron and the planet rotates slowly
25. Jupiter's moon, Io, is in a highly eccentric orbit. This means that Io spends alternate times in its orbit near and far from Jupiter. Knowing this, you could hypothesize that Io's volcanic activity could be caused by:
a. nuclear heating in the core
b. chemical reactions in the core
c. extreme atmospheric pressure
d. internal heating of the satellite interior by tidal stresses
NAME __________________________________ LAB # ____________________
Astronomy 1001 - Midterm #2 - April 6th Dr. Robert Gehrz- Spring 2005
Part II. Five (5) Short Essays (16 pts. each)
1. Many rocks in the crust of the earth contain traces of massive radioactive nuclei like Radium and Uranium. Explain how these elements were produced during the evolution of the Universe.
2. Draw and label an H-R diagram. Label the axes and show where the main sequence stars, the red giants, supergiants, and white dwarfs lie on the diagram. Indicate the position of the sun.
(over for #3 & #4)
NAME __________________________________ LAB # ____________________
Astronomy 1001 - Midterm #2 - April 6th Dr. Robert Gehrz- Spring 2005
3. Explain how a star like the sun can exist in a state of stable equilibrium without continuously contracting because of terrific force of its own self gravity.
4. We can determine the distances to nearby stars by using the method of trigonometric parallax. Explain how this method works. What do you think causes the largest uncertainty in the distances determined by this method?
NAME __________________________________ LAB # ____________________
Astronomy 1001 - Midterm #2 - April 6th Dr. Robert Gehrz- Spring 2005
5. List as many things as you can that observations of Supernova 1987a taught us about the evolution of massive stars.