You have to decide which chapter each question comes from and whether that chapter will be on your exam. Be very careful.

1. (10 points)

a) How long does it take light to travel from the Sun to the Earth?

b) What is the typical distance between stars in our part of the Milky Way Galaxy?

c) About how far away is the Andromeda Galaxy?

d) About how many stars are in our galaxy?

e) What is the approximate diameter of the Milky Way Galaxy?

2. (15 points) Below we have a sketch of the Sun and Earth (not drawn to scale) with part of the Earth lighted by the Sun and part in the shadow, along with the axis of rotation of the Earth (from N to S) and its two poles. We also have Oneonta located along with the dashed line to represent the path Oneonta takes as the Earth rotates.

a) For this particular diagram what season is it in the northern hemisphere? And what is the date (month and day).

b) With the aid of this sketch (or one like it) in a paragraph or two explain why we have seasons on the Earth. (I want a reasonably complete explanation. This diagram shows the Earth at one time of year. You will have to produce a second diagram showing the Earth six months later and explain why we have different seasons then.)

c) What time of day is it in Oneonta shown in the figure above.

3. (10 points)

a) About how long does it take the Moon to go around the earth once?

b) In approximately what year did Ptolemy propose his geocentric model?

c) In approximately what year did Copernicus propose his heliocentric model?

d) List two things that Galileo saw with his telescope that helped convince people that the geocentric models were not correct. (Just a short list; no explanations necessary.)

e) Who first proposed that planets orbited the Sun in elliptical orbits?

4. (10 points)

a) In a paragraph what is Newton's universal law of gravitation? (Be sure to describe how the force of gravity depends upon masses and distances.)

b) Give a clear description (perhaps similar to one that Newton might have given) of a satellite orbiting the Earth. In particular explain why it goes around the Earth and just does not fall and crash into the Earth. You might want to include a figure of the Earth and the paths of projectiles near the surface of the Earth.

5. ( 2 points) Light is both a wave and a particle. True or false?

6. (2 points) A gamma ray photon carries more energy than an x-ray photon. True or false?

7. (2 points) Gamma rays travel through a vacuum slower than 186, 000 miles/ second. True or false?

8. (2 points) Living people behave like black bodies. True or false?

9. (2 points) The total energy given off by a black body is determined completely by the temperature of the black body. True or false?

10. (10 points) Consider the two black body spectra shown below. One is produced by object A and the other by object B.

a) Which object is hotter, A or B? Clearly explain how you arrive at your answer.

b) Consider object B. What would be the color of the light coming from this object? (Reddish, bluish, whitish?) Explain how you arrive at your answer.

11. (2 points) Absorption lines in the spectrum of the Sun are produced a) when electrons in atoms are collisionally excited, b) when fusion produces positrons which are absorbed by dense gases in the outer part of the Sun, c) by light from the photosphere being absorbed by cooler atoms in the chromosphere, or d) by light from the photosphere passing through the much hotter corona. Pick one.

12. (2 points) Emission lines occur a) when photons move from higher energy levels to lower energy levels, b) only after electrons have first been excited to higher energy levels, c) only in very cool gasses, or d) when electrons convert themselves into photons and positrons. Pick one.

13. (2 points) Astronomers have observed that the light from many distant galaxies is red shifted. They conclude that a) the blue portion of the spectrum has been absorbed the interstellar gas, b) the galaxies are moving toward us, c) the galaxies are moving away from us, or d) the galaxies are somewhat cooler than the white Sun. Pick one.

14. (2 points) The luminosity of a star depends upon a) the temperature and distance of the star, b) the temperature and the wavelength of the star, c) the distance and the size of the star, or d) the temperature and the size of the star. Pick one.

15. (2 points) Some types of electromagnetic waves are mostly absorbed when they encounter the Earth's atmosphere. These include a) visible light, b) radio waves, c) gamma rays, or d) microwaves. Pick one.

16. (6 points) In a paragraph or two, why is it necessary to have high temperatures in order to get hydrogen fusing to fuse other hydrogen nuclei? Why can't it happen at lower temperatures?

17. (7 points) What is a spectroscopic binary? In a paragraph or two describe how they are detected and how astronomers know they are binary star systems?

18. (12 points) Observations of binary stars are important because they allow astronomers to determine a great deal about the individual stars.

a) In a sentence or two how do astronomers determine the speeds at which stars are moving in a binary system?

b) In a sentence or two how do astronomers determine how long it takes stars to go around each other in spectroscopic binary systems?

c) How do astronomers determine the distance between binary stars in a spectroscopic binary system?

9. (5 points) The figures below show the orbits of three objects (A, B and C) going around the Sun. We assume the motions of these objects obey Kepler's laws.

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This page prepared by C. Hartley, Director of the Ernest B. Wright Observatory at the Department of Physics at Hartwick College in the City of Oneonta, NY. More things from C. Hartley at his home.

All text, graphics and photgraphs copyright ©2003 by C. Hartley unless otherwise noted.