PART I: MULTIPLE CHOICE QUESTIONS (50 Pts

ASTR 101 Deming Fall 2001 EXAM I

PART I: MULTIPLE CHOICE QUESTIONS (50 pts.) Using what you have learned in ASTR 101, choose the BEST answer to each of the following questions and indicate your choice on the answer sheet. (2 pts. each)

1. Venus is sometimes referred to as Earth's twin. Why? A. Venus orbited Earth at one time. B. Both have similar temperatures. C. Both have a single natural satellite. D. They have similar mass and size. E. It has been determined that life evolved on both planets.

2. The planets of our solar system formed A. out of a flattened disk of gas and dust. B. in outer space and were later captured by the Sun. C. as another star collided with our Sun. D. a few million years ago. E. closer to the Sun but were flung outward by a passing star.

3. The ecliptic is A. the Sun's annual path around the celestial sphere. B. the path across the celestial sphere followed by comets. C. the line on the celestial sphere directly above the Earth’s equator. D. the point directly overhead. E. the line that divides the sky into the northern and southern hemispheres.

4. A large amount of the ultraviolet light from the Sun is prevented from striking the Earth's surface due to A. the Earth's magnetic field. B. atmospheric water vapor. C. the ozone layer in the stratosphere. D. gravity. E. airglow.

5. An observer at the North Pole A. sees no circumpolar stars. B. sees only circumpolar stars. C. sees a mixture of 40% circumpolar stars and 60% non-circumpolar stars. D. sees a mixture of 60% circumpolar stars and 40% non-circumpolar stars. E. sees a mixture of 50% circumpolar stars and 50% non-circumpolar stars.

6. When would you expect to be able to show someone earthshine? A. after consuming large quantities of moonshine B. during a solar eclipse C. during a lunar eclipse D. near an equinox E. whenever the Moon is a thin crescent

7. What keeps the Moon in a stable orbit rather than falling straight to Earth in response to gravity? A. It is weightless. B. It has inertia. C. The Moon’s force of gravity on Earth keeps them separated. D. Both Moon and Earth have the same charge so they repel. E. The Moon’s magnetism is opposite to that of the Earth.

8. A solar eclipse does not occur every month because A. sometimes a full moon does not occur. B. the Moon always keeps the same side toward the Earth. C. the Moon's orbit is inclined to the Earth's orbit. D. sometimes the Moon is at perigee. E. sometimes the Moon is at apogee.

9. Alignments like those found at Stonehenge in England, the Sun Dagger in New Mexico, and the Medicine Wheel in Wyoming suggest that the people who built these structures had knowledge of A. eclipse prediction. B. precession. C. retrograde motion. D. the position of the Sun on the summer solstice. E. supernovae.

10. On Earth your dog weighs 90 pounds. You decide to send your dog to another planet. This planet has the same mass as Earth, but its radius is three times larger. What would your dog weigh? A. 90 pounds B. 900 pounds C. 270 pounds D. 30 pounds E. 10 pounds

11. In order for carbon dioxide to be removed from a planetary atmosphere and trapped in carbonate rocks, ______must be present on a planet’s surface. A. a greenhouse effect B. liquid water C. volcanic activity D. radioactive decay E. ozone

12. Why is the surface of Venus hotter than that of Mercury? A. Venus rotates more slowly so it bakes more in the Sun’s heat. B. Clouds in Mercury’s atmosphere reflect sunlight back into space and keep its surface cool. C. Carbon dioxide in Venus’s atmosphere efficiently traps heat radiating from its surface. D. Venus is closer to the Sun. E. Venus’s rapid rotation generates strong winds that heat the ground by friction as they blow.

13. Using information brought back by the astronauts of the Apollo missions to the Moon, astronomers revised their theory of lunar formation. According to this new theory, A. the Moon resulted after a collision occurred between Earth and a body half its size. B. the Moon formed near Mars and was later captured by the Earth. C. a comet hit the Sun and material was thrown off that became the Moon. D. an asteroid hit the Sun and material was thrown off that became the Moon. E. the Moon formed beyond Pluto’s orbit and was later captured by Earth.

14. The average density of Earth compared to that of its surface rocks implies that the Earth A. has a core containing dense materials. B. has a liquid core. C. has a core containing low density elements. D. contains large amounts of trapped gases inside. E. contains large amounts of trapped water inside.

15. On the Autumnal Equinox, Sept. 22, the Sun was visible above the horizon for 12 hours and 9 minutes rather than exactly 12 hours. Why? A. The equinox occurred during the early morning, so on Sept. 23 the Sun was above the horizon for exactly 12 hours. B. For our latitude the Sun is always above the horizon for more than 12 hours. C. This year was not a leap year. D. Atmospheric refraction lengthens the time that the Sun is visible above the horizon for a few minutes longer at sunrise and sunset. E. The Sun was visible in the southern part of the sky.

16. Newton's three laws of motion or gravitational theory fail to explain or describe A. escape velocity. B. the rocket trike demonstration. C. the feather and ball dropping at the same rate in the vacuum demonstration. D. inertia. E. the generation of Earth's magnetic field.

17. Hipparchus discovered that the Earth's rotational axis precesses with respect to the stars. This causes A. refraction. B. reflection. C. the North Celestial Pole to change position. D. eclipse shadows to miss during most months. E. retrograde motion.

18. You fell asleep studying for your astronomy exam. You wake up and look outside. It is dark and you see the moon as shown. Estimate the time.

DRAWING WILL BE PROVIDED IN DISCUSSION SECTION

A. it is about 8 PM B. it is about midnight C. it is about 2 AM D. it is about 4 AM E. it is about 6 AM

19. Mercury is best described as A. the planet most like Earth. B. having a very heavily cratered surface. C. being primarily composed of light gases. D. having a surface covered with volcanoes. E. a place that shows evidence of water erosion in the distant past.

20. The atmospheres of Venus and Mars are similar in which way? A. They have the same temperature. B. They have the same pressure. C. They are mostly carbon dioxide. D. There are sulfuric acid droplets in the clouds. E. They contain a large number of ozone particles.

21. Standing on the surface of Venus you would experience A. violent sulfuric acid rain storms. B. darkness all of the time. C. tremendous crushing atmospheric pressure. D. a drastic temperature drop when night occurs. E. all of the above

22. The most abundant gas in Earth's atmosphere is A. hydrogen. B. nitrogen. C. oxygen. D. water vapor. E. carbon dioxide.

23. Today Astrology A. is a well respected branch of Astronomy. B. lacks support for its claims when examined using the scientific method. C. has numerous statistical and scientific studies to support its claims of accuracy. D. has mathematical formulae which relate its predictions to distance and mass. E. can be used to predict events with complete accuracy.

24. As a group, the terrestrial planets are ______than the jovian planets. A. more massive, larger, and less dense B. more massive, larger, and denser C. more massive, smaller, and denser D. less massive, smaller, and denser E. less massive, smaller, and less dense

25. Astronomers are convinced that liquid water was present on Mars in the past because A. huge subsurface deposits of ice have been seen with X-ray telescopes. B. during each martian summer large lakes are observed as the polar cap melts. C. there is a huge amount of water vapor in martian clouds. D. the surface has water-cut channels on it. E. we have seen dark vegetation growing along the canals.

PART II: SHORT ANSWER QUESTIONS (50 pts.) Answer as completely as you can using what you have learned in ASTR 101. After you have finished, go back and re-read the question to be sure that you have answered correctly.

26. a) As done in class, carefully sketch a celestial sphere to represent the sky for an observer at 25 degrees North latitude. Label any important angles for clarity. Indicate: the NCP, the SCP, the horizon, the zenith, and the celestial equator. (6 pts.) b) The planet Vulcan has an orbit that brings it as close as 1 AU from its star and as far as 3 AU. Make a labeled sketch of this orbit. Calculate the semimajor axis of the orbit. (4 pts.)

EXTRA CREDIT (2 points max) Use Kepler's third law to estimate Vulcan’s (see part b above) orbital period. Show your setup and work.

27. a) The Greeks rejected the heliocentric theory based on the parallax test. Describe their reasoning. (4 pts.) b) How did the work of Tycho, Kepler, and Galileo contribute to supporting the heliocentric theory? (What did they do and why was it significant?) (4 pts.)

EXTRA CREDIT (2 pts. maximum) What is the "summer triangle?"

28. a) List one of the telescopic observations made by Galileo. (2 pts.) b) Thirty years ago, we did not know what the surface of Venus was like. What was the problem and how was it solved? (4 pts.) c) Compare the volcanoes on Earth and Mars. Account for any differences. (3 pts.) 29. a) It is summer in the southern hemisphere. Make a sketch showing the Sun and Earth for this situation. Label your sketch for clarity. (4 pts.) b) Explain why it would be warmer in the southern hemisphere than in the northern hemisphere at this time of year? (3 pts.) c) Which atmospheric gas makes the greatest contribution to Earth’s greenhouse effect? (2 pts.)

30. Use this diagram for questions a-e.

DIAGRAM WILL BE PROVIDED IN DISCUSSION SECTION a) At which position would the Moon look like this: (1 pt.) b) Name the lunar phase shown above. (2 pts.) c) At what time will the moon set?______(1 pt.) d) An astronaut on the Moon looks toward Earth and sees Earth. Sketch Earth's appearance and name the phase. (2 pts.) e) Carefully draw the arrangement of the Sun, Earth and Moon on the day of a solar eclipse. (2 pts.)

31. a) Describe 2 processes by which a crater can be destroyed on Earth. (4 pts.) b) Explain why these processes happen on Earth but do not occur currently on the Moon. (2 pts.)