<p> PH109 Exploring the Universe, Test #3, Spring, 1999</p><p>NAME______</p><p>Indicate the best answer to the following questions on the answer sheet provided. Please answer the essay questions on the last page.</p><p>1. The four brightest moon of Jupiter are called a) Jovian moons, b) Galilean moons, c) Tycho’s moon, d) Shephard’s moons</p><p>2. This Jovian planet has very pronounced cloud zones, and bands and a cyclone storm that has lasted over 200 years a) Jupiter, b) Saturn, c) Uranus, d) Neptune</p><p>3. Which of the following Jovian planets has rings? a) Jupiter, b) Saturn, c) Uranus, d) Neptune, e) all the above</p><p>4. Which of the following Jovian planets have been visited by spacecraft? a) Jupiter, b) Saturn, c) Uranus, d) Neptune, e) all the above</p><p>5. Which is the most massive Jovian planet? a) Jupiter, b) Saturn, c) Uranus, d) Neptune, e) all the above</p><p>6. If you could find a bathtub big enough, which of the Jovian planets would float in water? a) Jupiter, b) Saturn, c) Uranus, d) Neptune, e) all the above</p><p>7. What element is most abundant in the Jovian planets a) Hydrogen, b) Helium, c) Methane, d) Ammonium</p><p>8. This Jovian planet almost had the name “George” a) Jupiter, b) Saturn, c) Uranus, d) Neptune, e) all the above</p><p>9. The surface of Jupiter is a) just beneath the cloud layer, b) about 100 miles deep, c) mostly frozen ice, d) does not exist</p><p>10. Even though Io is a small moon of Jupiter’s it is still geologically alive and keep warm by a) radioactivity, b) tidal forces, c) Jupiter's magnetosphere, d) asteroid collisions</p><p>11. The rings seen around planets are most probably caused by a) material escaping the surface of the planet, b) material being swept up by the planet c) a moon torn apart by tidal forces, d) part of the accretion process</p><p>12. Shepherd moons are a) moons first seen by the shepherds, b) moons first predicted by shepherds, c) moons which resemble shepherds, d) moons which shepherd rings</p><p>13. How many distinct ring sets are the rings of Saturn made of a) thousands, b) 5, c) they are a solid sheet of material, d) none 14. In terms of the speed of light, how far away is the Sun a) 8 minutes, b) 8 seconds, c) one parsec, d) 3 seconds</p><p>15. Sunspots appear dark because a) they are cooler regions, b) they are concentrations of carbon, c) their spectrum has been Doppler shifted, d) impurities in the Sun</p><p>16. The magnetic field in the Sun gets twisted around the surface because of a) tidal forces, b) gravitational influence by the planets, c) the sun rings like a bell, d) differential rotation</p><p>17. Material boiling off the surface of the Sun tends to follow curved trajectories because a) conservation of angular momentum, b) they follow magnetic field lines, c) the solar wind blows they around, d) the curved surface of the Sun</p><p>18. The source of energy in the core of the Sun is nuclear fusion. How many Hydrogen nuclei does it take to make one Helium nuclei a) four, b) nine, c) one, d) Hydrogen does not make Helium</p><p>19. In relative terms, how does the Sun's size compare to all other stars a) tends to be on the smaller side, b) tends to be on the larger side, c) tends to be in the middle, d) we can't measure the size of other stars</p><p>20. In relative terms, how does the Sun's temperature compare to all other stars a) tends to be on the hot disc, b) tends to be on the cool side, c) tends to be in the middle, d) we can't measure the temperatures of other stars</p><p>21. What is the correct sequence of spectral types of stars according to temperature a) OBAFGKM, b) OFGBGMA, c) FABOGKM, d) ABFGKMO</p><p>22. If I plot all known stars on the HR diagram, where will most of them be found a) red giants, b) blue giants, c) main sequence, d) major sequence</p><p>23. In order to measure the mass of a star what must be true a) it must be spectral type O or B, b) it must be a main sequence star, c) it must be close to Earth, d) it must be a binary</p><p>24. Which spectral type of star has the longest life on the main sequence a) O, b) F, c) K, d) M</p><p>25. About how far away is the nearest star after our Sun a) one light year, b) four light years, c) four parsecs, d) one astronomical unit</p><p>26. Star A and star B have the same luminosity but star A is four time brighter than star B. What must be true. a) they have different spectral types, b) star b is twice as far away, c) star A is exploding, d) star A is moving toward us</p><p>27. The dark regions and lanes seen in the Milky Way are a) regions of enhanced carbon concentrations, b) regions of no stars, c) regions cool dust and gas, d) regions of Doppler shifted light</p><p>28. The red color seen in many emission nebula is caused by a) Hydrogen atoms, b) Helium atoms, c) reddening, d) fire</p><p>29. The blue color seen in many nebular is caused by a) Hydrogen atoms, b) Helium atoms, c) reddening, d) Doppler shifted light</p><p>30. When the electron and proton go from aligned spins to opposite spins in the Hydrogen atom. What happens? a) nuclear fusion, b) nuclear fission, c) 21 cm radiation, d) E=MC2</p><p>31. About how long does it take a star like our Sun to form from a cloud. a) one million years, b) 10 million years, c) 1 billion years, d) 10 billion years</p><p>32. About how dense is the interstellar medium a) one atom per cm3, b) 10 atoms per cm3, c) about like Earth's atmosphere, d) about like the Jovian planets</p><p>33. The most common element found in the interstellar medium is a) Hydrogen, b) Helium, c) Carbon, d) ammonia</p><p>34. The study of the ringing and vibrations in the Sun is called a) solar complexity, b) helio reprocity, c) helioseismology, d) solar neutriology</p><p>35. Which planet is most likely to be hit by a comet or an asteroid a) Earth, b) Mars, c) Jupiter, d) Saturn</p><p>36. The nearest giant molecular cloud is located in a) the Milky Way, b) Taurus, c) Gaspra, d) Orion</p><p>37. The H-R diagram is a graph that plots a star's a) luminosity against its diameter, b) diameter against its temperature c) age against its luminosity, d) luminosity against its temperature</p><p>38. Which of the following planets occasionally has its poles pointed almost directly at the Sun? a) Mercury, b) Venus, c) Saturn, d) Uranus</p><p>39. What is meant by the statement that Pluto's rotation is synchronous? a) its rotation period is the same as that of Earth b) it always keeps the same face turned to the Sun c) it always keeps the same face turned to the Earth d) it always keeps the same face turned to its satellite</p><p>40. Suppose a planet is orbited by a number of satellites. Which of the satellites will feel the strongest tidal forces due to the planet? a) a large satellite in a close orbit, b) a large satellite in a distant orbit c) a small satellite in a close orbit, d) a small satellite in a distant orbit</p><p>41. (10 points) Listed below are the HR diagrams of two star clusters. Which one is older and how can you tell.</p><p>42. (10 points) Explain what the sunspot cycle is and what causes it.</p>