MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

Transcription

1 ASTRO 102/104 Practice Exam #3 Name Section MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) What is meant by a hypothesis? A) a natural phenomenon that requires explanation B) a tentative understanding of a natural phenomenon C) a pseudoscientific idea D) a historical theory that has been proved inaccurate E) an explanation for a phenomenon that makes a prediction 1) 2) Which of the following is NOT a class of known asteroids? A) Vulcanoids B) Centaurs C) Apollos D) Trojans E) Amors 2) 3) Which of the following best describes Pluto in terms of the general characteristics of terrestrial and jovian planets? A) size and distance most similar to terrestrial planets; composition similar to jovian planets B) density similar to terrestrial planets; temperature and composition similar to jovian planets C) size most similar to terrestrial planets; distance more similar to jovian planets D) temperature similar to terrestrial planets; distance and density similar to jovian planets E) size and composition similar to terrestrial planets; distance more similar to jovian planets 3) 4) Which of the following does not yield information on the internal structure of jovian planets? A) laboratory studies and theoretical models B) spectroscopy of the cloud layers C) spacecraft measurements of magnetic and gravitational fields D) detailed observations of planetary shapes E) Earth-based observations of the mass and size of the planets 4) 5) Why is Jupiter denser than Saturn? A) It is made of a different composition than Saturn, including a higher proportion of hydrogen compounds and rocks. B) Its core is much larger than Saturn's. C)The extra mass of Jupiter compresses its interior to a greater extent than that of Saturn. D) It has a greater proportion of helium to hydrogen compared to Saturn. E) It is unknown why this is so. 5) 1

2 6) Why does Jupiter have several distinct cloud layers? A) Different layers represent clouds made of gases that condense at different temperatures. B) Winds prevent clouds from forming at some altitudes, so we see clouds only at the other altitudes. C) Different layers represent the various regions where the temperature is cool enough for liquid water to condense. D) Clouds form randomly, so on average there are always several layers. E) Jupiter's atmosphere is not "well mixed" - it has layers of different gases 6) 7) Suppose the jovian planet atmospheres were composed 100 percent of hydrogen and helium rather than 98 percent of hydrogen and helium. How would they look different? A) they would all be bland and colorless B) they would all be stars undergoing nuclear fusion C)they would all have NO clouds D) they would all be blue like Neptune is now E) A and C 7) 8) Why is there no large temperature variation from the poles to the equator on Jupiter? A) Jupiter absorbs the same amount of energy from the sun at all latitudes. B) Jupiters many moons reflect additional energy to the poles. C) The surface temperature on Jupiter is determined more by internal heat than by solar radiation. D) The strong magnic field ensure that there temerpature at the poles is the same as the equiator. 8) 9) Jupiter and the other jovian planets are sometimes called "gas giants." In what sense is this term misleading? A) They are not in any sense "giants." B) They actually contain a significant fraction of non-gaseous matter. C) Actually, it's a great description, because these worlds are big and gaseous throughout. D) The materials they are made of are not the kinds of thing we usually think of as gases. 9) 10) Pluto is a(n) A) dwarf planet. B) planet. C) asteroid. D) Trans-Jovian Object (TJO). E) demi-planet. 10) 11) What are the spokes in Saturn's rings? A) large, elongated rocks in the rings B) dark particles in the rings C)gaps between the particles in the rings D) shadows caused by larger rocks in the rings E) particles of dust suspended above the rings by magnetic forces 11) 12) Which of the following Pluto observations did not help convince scientists to change Pluto's status from that of a planet? A) discovery of Pluto's 3 moons B) discovery of seasonal atmosphere, similar to comets C) discovery of the Kuiper Belt D) discovery of large Kuiper Belt Objects 12) 2

3 13) What is Charon? A) a satellite of Pluto B) a satellite of Neptune C) the largest known comet D) one of the Galilean moons of Jupiter E) the largest known asteroid 13) 14) Why are Saturn's rings different from the rest of the jovian planets' rings? A) They're composed of water ice. B) They're solid. C) They're composed of gas. D) They're composed of carbonaceous material/organics. E) The individual particles that make up the rings move in Keplerian orbits. 14) 15) Which of the following does NOT contribute significantly to ring formation? A) Impact ejecta from the planet. B) Impact ejecta from small moons. C) Shattered small moons. D) Neither A nor B. E) Neither B nor C. 15) 16) According to the IAU resolution regarding planets, which of the following statements is TRUE? A) A planet can be in orbit around any star. B) A dwarf planet must have cleared the neighborhood around its orbit. C) The category "Small Solar System Bodies" includes satellites. D) A dwarf planet can be a satellite. E) A planet has enough self-gravity to be nearly round. 16) 17) The Trojan asteroids are in a 1:1 orbital resonance with Jupiter. Jupiter's orbital period is about 12 years. What is a good estimate of the Trojans' orbital semi-major axis in AU? A) 9.6 B) 4.0 C)1.0 D) 2.5 E) ) 18) What is the approximate mass of objects in the asteroid belt? A) 0.1 Lunar mass B) 1 Jupiter mass C)1 Earth mass D) 1 Lunar mass E) 1 Solar mass 18) 19) What is a possible origin of iron-rich main-belt asteroids? A) They originated from the mantle of a terrestrial planet B) They were placed there by an alien civilization C) They came from a differentiated, impact disrupted parent body. D) These asteroids formed directly from an iron-rich region of the solar nebula 19) 3

4 20) Where do most long-period comets come from, and how do we know? A) The Oort cloud; long period comets tend to be in the plane of the solar system, just like the Oort cloud. B) The Kuiper belt; long period comets tend to come from random directions indicating a spherical distribution of comets called the Kuiper belt. C) The Oort cloud; long period comets tend to come from random directions indicating a spherical distribution of comets called the Oort cloud. D) The asteroid belt; long period comets have orbital periods similar to asteroids like Vesta, and are found in the plane of the solar system just like the asteroid belt. E) The Kuiper belt; long period comets tend to be in the plane of the solar system, just like the Kuiper belt. 20) 21) The four Galilean moons around Jupiter are A) a mixture of rock and ice, with the ice fraction increasing with distance from Jupiter. B) all made of rock. C) a mixture of rock and ice, with the rock fraction increasing with distance from Jupiter. D) hydrogen and helium gas. E) all made of ice. 21) 22) What is the most important reason why an icy moon is more likely to be geologically active than a rocky moon of the same size? A) Ice has a lower melting point than rock. B) Ice contains more radioactive elements than rock. C)Ice is less rigid than rock. D) Ice is less dense than rock. E) Ice is affected by tidal forces to a greater extent than rock. 22) 23) Which characteristic of Io's orbit is most responsible for the moon's tidal heating? A) Longitude of the ascending node B) Distance from Europa C) Eccentricity D) Speed E) Inclination 23) 24) Why does the dust tail of a comet curve? A) The dust tail extends in a Keplerian orbit along the comet's curved orbital path. B) The dust tail is actually straight, it just appears curved due to its orientation. C)The dust tail particles recede from the sun due to radiation pressure, and fall behind the comet in a curved tail as they follow Keplerian orbits. D) Outgassing from the comet's surface launches dust particles inward toward the sun on curved orbits. E) The sun's gravity pulls dust particles inward, forming the curved dust tail. 24) 25) Tunguska-sized impacts should take place every few hundred years. Why are there few historical records of them (other than the Tunguska event itself)? A) Such impacts of that size never occur on earth throughout the human history. B) The impacts are devastating and leave no survivors to tell the tale. C) Meteorites of that size often explode before they hit the ground, leaving no impact crater. D) The world governments conspire to hide all the historical records from their citizens. E) Most impacts occur in remote and unpopulated area, most likely oceans. 25) 4

5 26) Which of the following does not explain why there is a small chance for a major impact to occur on Earth? A) The presence of large jovian planets B) There are relatively few asteroids near the Earth C) Most asteriods are small in diameter D) Earth's thick atmosphere and oceans E) All of the above actually reduce the chance of a major impact. 26) 27) In the asteroid impact theory of the extinction of the dinosaurs, the dinosaurs (and over half of all the other species on Earth at that time) died off largely because A) the impact caused massive earthquakes and volcanic activity worldwide. B) dust injected into the stratosphere from the impact absorbed visible light from the Sun, causing global temperatures to plummet and halting photosynthesis. C) dust settled on the leaves of plants, stopping photosynthesis and making them inedible, so the animals died of starvation. D) of injuries suffered from direct hits of pieces of the asteroid or comet. E) radiation from iridium in the asteroid caused the dinosaurs to die of cancer. 27) 28) On average, how often do impactors about 10 km in size, large enough to produce mass extinction, hit Earth? A) once every hundred million years B) once every thousand years C) once every century D) once every million years E) once in Earth's history 28) 5

6 Answer Key Testname: ASTRO102_PRACTICE_EXAM3 1) E 2) A 3) C 4) B 5) C 6) A 7) E 8) C 9) B 10) A 11) E 12) A 13) A 14) A 15) A 16) E 17) E 18) A 19) C 20) C 21) A 22) A 23) C 24) C 25) E 26) D 27) B 28) A 6